Category Archives: Gemstones

    How gemstone hardness measured

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    How gemstone hardness measured

    by Binashaji

    Diamonds measure 10 on the MOHS scale and Aquamarine measures 7 whereas Pearls can measure between 3 and 4 on the MOHS scale. MOHS is a term oft used in Gemstone Jewelry, but what exactly does MOHS mean and signify?

    The MOHS scale was formulated in the 1800’s by a German mineralogist (Geologist) named Friedrich Mohs. As a Geologist, he spent over a decade studying and experimenting with various minerals and gemstones. Friedrich Mohs created an easy to remember scale by which one could easily discover if a mineral was delicate or hard. The resultant MOHS scale makes it possible to gauge the scratch ability of a mineral or gemstone. He took 10 minerals and gave each one a number from 1 to10 depending on its hardness as compared to the minerals above and below it. The MOHS scale is given below:

    The symbol for MOHS is HM.

    Mohs Scale of Hardness
    1Talc (softest)
    2Gypsum
    3Calcite
    4Fluorite
    5Apatite
    6Feldspar
    7Quartz (Amethyst)
    6.5 – 7.5Garnet
    7.5Beryl (Emerald)
    8Topaz
    9Corundum (Ruby and Sapphire)
    10Diamond (hardest material known to man)

    Although Friedrich Mohs designed this model for minerals in general, it is not used scientifically in laboratories because it is not an exact measurement. The MOHS scale is only a comparative scale. The degree of the hardness is only to check if a gem can be scratched by another gem that is above or below it. For eg. Garnets and Amethyst are both rated as 7 on the MOHS scale and it means that both can scratch each other if they are handled without care or placed with each other. But if a Garnet is placed with a stone like opal which is 6 HM then the opal can be scratched by the Garnet. Alternatively if the Garnet is placed with a Ruby (hardness of 9) then the Garnet can get damaged but not the Ruby. So if new , unknown gem is discovered and its hardness is not known , it can be rubbed against various known gems. Depending on which material leaves scratches on it, it hardness on the MOHS scale can be arrived at with relative ease.

    The MOHS scale only determines the ability of the gemstone to resist scratches. It is not a measurement of the strength of the stone. A high MOHS rating does not necessarily mean the material is strong. For example a Diamond is 10 HM, which means that it measures 10 on the MOHS scale. Diamonds are the only substance with a rating of 10 on the MOHS Scale. They are the hardest gemstones known to man and Diamond bits are used to cut glass, metal and other diamonds also. Although Diamonds cannot be scratched easily, they are brittle. A light blow and a diamond can crack and break.

    There are several other exact scientific methods to arrive at the exact hardness of any material. It is not possible to decide that a stone which has a hardness of 3 is exactly half as hard as a stone which measures 6 on the MOHS scale. For eg. Corals measure 3.5 and an Amethyst is 7on the MOHS scale. But accurate scientific tests have shown that the hardness of the Amethyst is more than 20 times the coral. The numbers accorded to the stones on the MOHS scale are only for comparison and they are not proportionate with each other.

    But the MOHS scale has been a boon to the Jewellery industry and specially for the Gemstone buyers. This easy to remember scale makes it very easy to maintain and care for Gemstone Jewellery. This scale helps even a layman understand about how Jewellery should be maintained and stored. Storing Aquamarines with Pearls can be disastrous. The Aquamarine will scratch the delicate pearls leaving ungainly scratches which can be felt if a finger is rubbed gently across the Pearls. These scratches will even show up when light falls on the earrings or necklace, ruining the classiness of the Pearls.

    When buying Jewellery, just ask your Jeweler what is the MOHS rating of the gemstone. It is much easier to store and maintain Jewellery when you have an idea about the MOHS rating of piece you have bought. Corals, Pearls, Amber all are delicate and need to be used with care. As a rule, if your gem does not measure at least 7 on the MOHS scale, it is a delicate stone and can be damaged very easily. So extra care should be taken while wearing these ornaments.

    The MOHS rating can help determine the usage of the Jewellery too! For everyday wear, Diamonds are the best – their hardness is 10 and they do not get scratched easily. Rubies, Emeralds also are great for people with active lifestyles since they measure 9 on the MOHS scale and have a greater resistance.

    If you love wearing Gemstone Jewellery, get to know the MOHS scale to help you understand and care for your precious pieces. Although the scale is not an accurate measure and can only be used for comparisons, it is great to care for your precious ones !

    Amethyst in History

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    Amethyst in History

    by Mathew Abraham

    Since the color of amethyst is associated with royalty, it has been the natural choice for most monarchs from ancient times. Egyptian rulers had a marked preference for the stone. Some exquisite amethyst stones adorn the British Crown Jewels. Catherine the Great was also known to have a liking for this precious stone. Besides, rulers were expected to be sober in order to make proper decisions on important matters, and amethyst was believed to have the ability to protect the wearer from any kind of intoxicating influence.

    Summary: Since the color of amethyst is associated with royalty, it has been the natural choice for most monarchs from ancient times. Egyptian rulers had a marked preference for the stone. Some exquisite amethyst stones adorn the British Crown Jewels. Catherine the Great was also known to have a liking for this precious stone. Besides, rulers were expected to be sober in order to make proper decisions on important matters, and amethyst was believed to have the ability to protect the wearer from any kind of intoxicating influence. The stone has become symbolic with temperance. Leonardo Da Vinci found that the stone was able to protect him from evil thoughts and stimulate his intellect. The association with royalty makes it popular with the leaders of modern societies also, as it gives them the feeling of being “kings” in their respective areas. Since it is found in different locations around the world, it has become very popular. And were it not so abundantly available, it would have been very costly. It is a popular choice as a 17th wedding anniversary gift.Early History
    Available information suggests that this purple category of quartz was popular in several ancient civilizations. The stone was popular with hunters, and was credited with the power of giving protection during battle and against poisons. It was also believed to dispel sluggishness and increase mental agility. There is even a Biblical reference to it being one of the twelve stones to adorn the breastplate of the high priests. It was commonly used as an adornment, especially among the aristocratic classes. Though Pliny has opined that the name of the stone is derived from its color, which resembles wine, popular folklore connects the name to Greek origins. The theory suggests that the term ‘amethyst’ is derived from the Greek roots ‘a’ – meaning ‘not’ – and ‘methuskein’ – which means ‘intoxication’ – because it was believed that alcoholic drinks consumed from cups made of amethyst would not intoxicate the drinker. It was also believed to protect the wearer from amorous intoxications.
    And there is an interesting Greek legend concerning the origin of the stone itself. Dionysus, the Greek God of intoxication, had been offended by a mortal. In a fit of rage he decided to take revenge on the next mortal to cross his path, and created a vicious tiger to execute his deadly design. The next innocent who came that way turned out to be the beautiful young maiden, Amethyst, a devotee of the Goddess Diana. In order to save Amethyst from the tiger, Diana transformed her into the purest form of crystalline quartz. When the eyes of Dionysus beheld the incredibly beautiful statue, they shed tears of deep purple wine that stained the quartz and gave it its attractive color.There are other theories that connect the name to oriental sources, claiming that the present term is a corruption of the original name. During the middle ages, the stone became popular among the Catholic clergy, as it was believed that the anti-intoxicating properties of the gem would help them maintain their vows of celibacy. Amethyst came to symbolize piety and Bishops frequently used it for their rings. Other religions, Like Buddhism, also attached importance to the stone.Astrological and Mystical History
    Traditionally amethyst is the astrological stone of the star sign Pisces. Today it is also accepted as the stone for the month of February, and some people even connect it with the star signs Aries, Aquarius, Virgo, Capricorn and Sagittarius. The deep violet and purple colored varieties are the most popular as astrological and birth stones. Many people still attach a lot of importance to the traditional positive values attributed to the gem. It is associated with Saint Valentine as a symbol of pure love, chastity, temperance and faithfulness. Hunters and soldiers wore it to gain presence of mind and clear thinking in stressful situations. Many believe that wearing the gem can gain favors from royalty and other wealthy and powerful leaders of society. Amethyst is also accepted as a symbol of spirituality and detachment from worldliness, allowing the wearer to make wise decisions in worldly affairs (including business matters) even while keeping the mind occupied in philosophical realms.

    Other qualities attributed to amethyst include increase in faith and wisdom, diligence in prayer and religious practices, assistance in prophecy, protection from poisonous substances and sorcery, discernment and suppression of evil thoughts and evil forces, guidance for travelers, indications of deterioration in health, etc… It is credited with enabling the wearer to see and interpret prophetic dreams and visions concerning future events. It is also believed that wearing the gem can bring love and good fortune.

    Contemporary History
    In modern times amethyst has become very popular as it is readily available all over the world. Mines are located in the United States, Canada, Mexico, Brazil, Argentina, Bolivia, Uruguay, Zambia, Namibia, South Africa, Russia and Australia. Although there are marked differences in the quality of the stone depending on the place of its origin, all varieties are very much in demand. The South American amethyst is generally larger than the African variety, but the latter tend to have a deeper color. The Australian stone is very small in size but has a very dark color. Stones mined in Russia are clear and have a deep color.

    The gem comes in an attractive and wide array of colors that range from a deep purple to a pale lilac shade. The prime choice for ornaments is the translucent rich purple variety. These stones have a rose colored sparkle and are the most expensive. The paler pastel shades, referred to as “Rose de France”, are more suited for jewelry crafted in Victorian designs. These days amethyst is available in a wide variety of shapes and sizes. Though generally the stones are cut to standard dimensions, some of the more imaginative designs are very much in demand – especially those linked to some legendry folklore or mystical powers. But whatever the size, whatever the shape, and whatever the color, the demand for the stone is increasing everywhere.

    Factors affecting quality of pearls

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    Factors affecting quality of pearls

    by Bina shaji kurup

    An important factor in deciding the quality of the Pearl is its Luster. A high luster is visible in the reflections on the surface of the pearl – a clearer reflection signifies a better luster and such pearls seem to have a warm glow. The luster of the pearl is dependant on the thickness of the nacre coating on the pearl – it is normally understood that the longer a pearl is left inside the mollusk, the thicker is the nacre layer.

    How does one decide if a pair of pearl earrings or a necklace is worth its price? As with all gemstones, pearls too have certain factors, which decide their quality and price. Since pearls are natural creations and do not require cutting or polishing, it is rare to find uniform pearls unlike gemstones which can be cut and polished into uniform sizes. This is the beauty of the pearl, each pearl is unique and sometimes particular shades, sizes, and shapes can become scarce. Natural factors like water pollution, diseases, temperatures etc, all affect the availability of this delicate gem. Of late, with the advent of the pearl farms, the conditions are kept controlled giving better results and improved quality pearls. Some of the factors affecting the price and determining the quality of pearls are given.

    PearlAn important factor in deciding the quality of the Pearl is its Luster. A high luster is visible in the reflections on the surface of the pearl – a clearer reflection signifies a better luster and such pearls seem to have a warm glow. The luster of the pearl is dependant on the thickness of the nacre coating on the pearl – it is normally understood that the longer a pearl is left inside the mollusk, the thicker is the nacre layer. A good quality pearl will glow warmly and reflect images clearly. Pearls with thin nacre are not of good quality and will not have the glow of thick nacre pearls.

    Associated with the luster is the Surface of the pearl. Most pearls have some small blemishes or marks on the surface or they may slightly dented – this is more visible in larger pearls, although jewelers normally make sure the pearl is polished and sometimes treated to ensure its surface looks smooth and flawless. The pearl is a creation of nature and some flaws are normal in most pearls. But deep cracks or holes or overgrowths on the pearl or too many dents and blemishes should be avoided as they ruin the elegance of the pearl. A naturally flawless surface is extremely rare and such pearls are not made into jewellery, they are kept as they come from the oyster – without drilling holes or converting them into pieces of jewellery.

    Origin of the pearls is important while deciding on the quality and price. Natural pearls, which are rare, command a higher price and the saltwater cultured pearls are the next on the price range. Freshwater cultured pearls are the cheapest and are available to suit all budgets – from economical to expensive.

    The shape of the pearl is another factor in deciding the quality of the pearls. A round shape is highly valuable. This is because finding a perfectly rounded pearl is fairly rare – the Black Tahiti pearls are some of the rare examples of round pearls. White round pearls are normally rare. It is easier to find pearls in other shapes, the oval shape being less expensive and more readily available. Rice Pearl strands are eye-catching and are available in several designs. Thus the shape of the pearl although important in deciding the cost, is not important while purchasing a strand or pair of earrings since all shapes of pearls are equally enticing.

    Large pearls above 14mm size are rare and most freshwater cultured pearls (pearls grown on cultured pearl farms) range from 1mm to 12mm. The larger pearls are normally saltwater pearls like Tahitian and South Sea pearls in sizes from 12mm to 20mm (which are rare and most prized). Most Freshwater pearls are small ranging 1mm to 9mm. The diameter of the Pearl is measured in millimeters to get the exact size. Although large pearls are expensive, if they do not have a good luster or are flawed, it is safer to avoid buying them. Instead buying smaller sized pearls with a good luster is advisable.

    Silvery white, a gentle tinge of gold or pink, hues of black and blue – pearls are found in myriad colors. The color factor while deciding on a strand or a pair of earrings is a purely personal choice – some prefer the light shades of white, pink or gold whereas some love the look of the gray or black Tahitians. The colors most sought after are the whites with a tinge of rose in them and the colors most avoided are shades of green and brown. Ensure that you ask your jeweler if the pearls have undergone color enhancement, which has become a custom. Pearls that have not undergone color enhancement are rare.

    While buying strands or pearl necklaces, the size, shape and color of the pearls is very important.
    A necklace that does not have matching pearls can look shabby and cheap. In fact, expensive necklaces are those which have matching pearls – the size of the pearls is irrespective. A necklace could have the pearls of the same size, shape, color or they could be of varying sizes with the same shape and color. It is important that the strand looks uniform and has a certain balance in the pearls used. Uniformity and balance is the key to acquiring an elegant pearl necklace.

    Buying pearls with these qualities will make your purchase worth the price you pay for your elegant pair of earrings or the special bracelet or necklace.

    Amethyst Internationally Acclaimed Gem

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    Amethyst Internationally Acclaimed Gem

    by Mathew Abraham

    Now that amethyst is being mined all over the world, it is readily available internationally and has become very popular with jewelers. Its natural attributes (especially color, shape and size) vary according to the location from which it is mined. The stone comes in a dazzling array of enchanting shades that range from deep purples to pale lilac pastels. It is a much sought after gem because of its association with royalty, the wealthy and powerful, and also with certain religious leaders. Wearing the gem gives its owner a sense of belonging to a superior class in society. It is also believed to have many supernatural powers that are beneficial to the wearer. It is the internationally accepted choice as a gift for the 4th, 6th and 17th wedding anniversaries.

    International acceptance of Amethyst
    All collectors of gems and minerals are familiar with amethyst. Its widespread availability makes it easy to recognize. Even though the stones differ in nature depending on the location from which they are mined, experts are able to identify the original location of the stone by assessing its natural attributes. The gem comes in a wide range of colors, shapes and sizes, all of which are acceptable to collectors as well as jewelers. Most customers shopping for amethyst ornaments have different reasons for selecting the stone of their choice. Many are attracted to the mystical and astrological attributes credited to the stone. One such quality for which the stone is internationally famous is the belief that it prevents the wearer from becoming intoxicated. And it is not just from alcoholic intoxication, but also from other kinds of intoxication like the amorous or addictive kinds. It is also believed to give the wearer clarity of thought and temperance, qualities desirable in leaders of society and industry. This is the main reason why it has been internationally acclaimed as the “Royal Gem” for centuries. And it is for this reason that aristocratic, religious and political leaders from every part of the world can be seen wearing this stone even today.

    Amethyst is the official birthstone for the month of February and the astrological stone for the zodiac sign Pisces. It is also accepted as an additional stone for the zodiac signs Aries, Aquarius, Virgo, Capricorn and Sagittarius. As more and more people around the world are being attracted to astrological horoscopes, the demand for zodiac and birth stones is rapidly increasing. This factor has contributed to a considerable increase in the demand for amethyst internationally. Many people believe it brings true love and good fortune.

    The stone is credited with several other attributes that make it internationally renowned. It is believed to bring peace and tranquility to the wearer and make the person more tender-hearted and affable. It is also believed to have the power of cleansing the soul, removing any self-destructive and undesirable traits and replacing them with a purer form of spirituality. According to traditional reports, it has the ability to heal physical, emotional and mental disorders. Some persons are convinced that amethyst can deflect different kinds of energies directed towards the wearer, so that the person does not absorb them. They claim that the human intellect does not have the capacity to comprehend the manner in which these powers work. The stone is said to endow the wearer with psychic powers and the ability to see prophetic dreams that predict events about to take place in the future.

    International locations and standards of Amethyst
    Amethyst is essentially quartz, and some variety of quartz crystals can be found in practically every kind of rock formation. That is why amethyst is so readily available all over the world – although in different grades having a variety of colors, shapes and sizes. Even the structural formation varies from area to area. The commonly accepted method of identification is by its six-sided prismatic structure and its hardness value of 7 It has a specific gravity of 2.66 and a refractive index of 1.54 – 1.55.. The mineral composition is crystalline quartz and the chemical composition is SiO2. The best varieties are mined from deposits in Brazil, Sri Lanka, Japan, Mexico, Russia and South Africa. Other well known locations include Canada, Zambia, Bolivia, the United States, India, Madagascar, Germany, Australia, Namibia, Iran and Uruguay.

    The internationally accepted superior grades of amethyst are the Amethyst Quartz (a fusion of amethyst and milky quartz that either has purple and white bands or is purple on top and translucent beneath), Canadian Amethyst (having an inner glaze of red hematite and confined to Thunder Bay in Ontario), Ametrine (a purple and orange combination of amethyst and citrine), Lavender Amethyst (a pastel shade of pale purple) and Vera Cruz Amethyst (having a tall, prismatic structure and located in Vera Cruz, México). The best quality of amethyst is expected to have a rich purple or violet color with flashes of rose red. Though this variety is referred to as the “Siberian”, it is mined from many other locations like Uruguay and Zambia. Some pale violet pastels with a reddish tinge are also in demand. Light lilac, lavender and mauve are other common colors. The lighter pale shades are considered to be of a lesser standard, and the best of them are the pinkish lavender or lilac colored stone called the “Rose De France”. The purple corundum (or sapphire) is called the “Oriental Amethyst” even though it may not have any oriental origins.

    The color in most stones tends to fade or change over a period of time, particularly if subjected to heat and light. In fact most citrine, cairngorm and yellow quartz are formed as the result of artificially controlled heat and light application to amethyst. One such example is the “Ametrine”, so called because it develops alternate bands of purple (from amethyst) and orange (from citrine) after treatment. Today, most dealers in amethyst subject the stone to controlled degrees of heat treatment in order to heighten or change their color. Invariably the treatment has a permanent effect. Amethyst comes in a variety of shapes and sizes. Most are suitable for collectors but there is more demand for stones that can be cut for jewelry. Besides, because of the traditional folklore and legends associated with amethyst, many wearers require the stone to be cut in specific shapes for specific purposes.

    Amethyst – the international precious stone
    Because of its availability all over the world and because of the wide range available in color and price, amethyst has become a truly internationally acclaimed stone for all persons in all places. Its legendry healing and mystical powers add to the enchanting allure of the gem. And the fact that it is identified with royalty and the uppermost layers of society make the stone even more desirable

    How Pearls are graded

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    How Pearls are graded

    by Bina Shaji Kurup

    A good pearl has several qualities and based on these qualities pearls are graded. There are two systems of grading pearls, which are accepted worldwide. One system is the ‘Tahitian’ system developed by the Polynesian government. This system is used to grade Black Tahiti pearls and other Saltwater pearls like the South Sea pearls. The other is the ‘AAA-A’ system, which is used to grade cultured Freshwater pearls.

    The Tahitian System adopted mainly to grade Saltwater pearls grades pearls on a scale of “A” to “D”. “A” signifies pearls of the highest quality and “D” are the lowest quality pearls which can be used to make jewellery. Any pearl lower than “D” grade is not used to make jewellery and is not exported out of the country. Lower than “D” grade pearls are used to make pearl powder and are sold only in Tahiti. The Tahitian system of grading pearls works as follows:

    “A” quality pearls have a brilliant luster, reflecting images and colors clearly. They will have a clear surface with only 10% blemishes or flaws on the surface. These flaws are usually not visible since the hole is drilled over these flaws. Mainly these pearls are round in shape and their color is deep with overtones of Pink, Peacock Blue, Gold etc. These pearls are round in shape with a thick nacre coating, which is evident in the luster of the pearl. The pearls belonging to grade “A” are large pearls – more than 14mm in size. Grade “A” pearls are rare which makes them the most expensive pearls.

    Pearl Ring

    “B” quality pearls have a good luster and approximately one-third of the surface is flawed lightly. Their shape is round or semi-round and the flaws are often invisible from a distance and show up only on closer examination of the pearls. These pearls are between 12mm to 14mm in size with overtones of Gray, Pink, Gold etc.

    “C” quality pearls are lustrous and pearls having less than 60% minor imperfections come under this category. These pearls are normally semi-round and have a variation of more than 5% in their diameter. Although there is a difference between the “B” and “C” grade of pearls, an untrained eye cannot really pinpoint the difference. The size or luster may vary and the shape will not be as round as “B” grade pearls. The pearls in this category are smaller and their color may not be as pronounced as the “B” grade pearls.

    “D” quality is accorded to pearls if they have flaws like deep dents or cracks on the surface. Even pearls with high luster are graded D if more than two thirds of the surface is flawed.

    Pearls below “D” quality or with flaws covering more than 65% of their surface are not used for making jewellery. To understand the differences in luster and surface of the pearl, try comparing pearls of different grades, it is possible to get a better understanding of how pearls are graded!

    Black Tahitian pearls are renowned the world over and their color makes them unique. The beauty of these pearls is in their overtones. A plain black pearl costs much less than a similar pearl, which has overtones of Green, Pink, Gold Purple etc. (but brown shades are not considered to be a good buy) The exception to this rule is the large size pearls – exceeding 18mm, which are rare and are categorized as “A” grade irrespective of their color. Pearls with a mix of more than two colors are considered to be of a higher quality and command a higher price. Multicolor strands are famous in Tahiti and are absolutely eye-catching.

    The other system for grading pearls is the “AAA -A” system. Used mainly for grading freshwater and Akoya pearls, sometimes even saltwater pearls are graded under this system. In this classification, the pearls are graded as being “AAA” (the highest grade), “AA” being medium quality and “A” being accorded to pearls, which do not meet the requirements of either “AA” or “AAA” grades. As with the Tahitian system, the pearls are graded as per their size, shape, color, surface, nacre thickness and luster.

    “AAA” grade pearls are the ones with the highest luster, least blemishes on the surface and have a rounder shape (although perfect spheres are unusual in Freshwater pearls). These pearls have a thick nacre coating and are normally white with Pink or Gray overtones. Pearl strands cannot be of a higher grade than “AAA” grade and are expensive. Necklaces are also rare in this grade and most pearls are sold as strands or as individual pieces or as rings and pendants. These grades of pearls are the largest in size exceeding 8mm (sizes of 10mm or more amongst freshwater pearls are very rare)

    “AA” pearls have a good luster and their surface is slightly flawed but hidden by mounting or drilling the flawed area, whereby only the flawless surface is visible. Their shape may be less round than the “AAA” grade pearls but not of a semi-round shape or a baroque shape. Rolling a pearl along a straight surface determines its shape – a straight line signifies a round shape, a zig-zag line signifies the shape is semi-round and a semi- baroque shape will rotate on one side only. The semi-baroque shape is further divided into drop, button, pear and oval – all four shapes are nearly similar with small differences. “AA” grade pearls are found in shades of White, off-white or cream with pink, silver and green overtones. They are available in sizes of 5mm to 8mm and have medium nacre thickness.

    “A” grade pearls are available in many shapes and their natural shapes gives them a look that is unique yet elegant. These pearls have a flawed surface of more than 25%, but it is not visible from a distance. These pearls make an economical buy and are available in a variety of designs, a spectrum of colors and shapes like Rice or Seed pearls, Oval or pear shaped, Button and Baroque shapes. These are normally smaller size pearls between 1mm to 4mm in size. The nacre coating in these pearls is not as thick as pearls of “AA” and “AAA” grade pearls. But in no way does the lack of luster or size or shape reduce the beauty of these pearls.

    Pearl jewellery, especially Necklaces and Strands of pearls are made of several pearls and not all of them may meet the same classification, some may be of an “AA” quality whereas some maybe of “A” quality. Also mounting or drilling the pearls at the point of the blemish cleverly hides blemishes and a dishonest jeweler can pass of “A” grade pearls as “AA” pearls and sell them at a higher price. The Lustre of the pearl cannot be hidden and that would be the best test to determine whether a pearl necklace is of “A” grade or “AA” grade. It makes sense to check each pearl for luster and flaws before buying an expensive piece. If a strand of pearls is graded “AAA”, most of the pearls, if not all, must be of “AAA” quality.

    The main difference in both grading systems is that under the Tahitian system, pearls are graded only as A, B, C or D. Under the second system, it is possible for sellers to give grades, which are higher or lower than the specified grades like AA+ for pieces that do not meet the specifications but are in between two classifications. This gives the sellers a little more flexibility.

    Some sellers may tell you that the pearls sold by them are of “AAAA” quality, which is better than the “AAA” grade and not usually accepted as a grading measure. In such a scenario, remember some rules about “AAAA” pearls. “AAA” and “AAAA” pearls are different mainly in terms of their shape. “AAAA” pearls are the perfectly rounded pearls, which are very rare – especially in Freshwater cultured pearls. Since their availability is limited, these pearls are mainly used to make solitaire pieces like pendants and rings. A necklace or strand of pearls in the “AAAA” grade is almost impossible to find. They have a flawless surface and are normally smaller in size.

    Pearls are delicate gems measuring 2.5 to 4 on the MOHS scale. Even our tooth enamel can leave scratches on its beautiful surface. Always buys pearls with a thick coating of nacre – which will protect it from cracking (in case it falls), discoloration and age.

    Store your pearls separately away from other jewellery and remember the golden rule of wearing jewellery – ” always put it on last and remove it first”. This means that only after applying make-up, dressing up, spraying on perfume etc and finishing every aspect of getting ready should you wear your jewellery to protect it against any chemicals contained in sprays or cosmetics. Similarly, remove your pearls first and keep them safely to ensure they do not get damaged. Pearls do not need to be washed; just a mild rub with a dry cloth will remove accumulated oils and dirt and restore their luster. At regular intervals, return your pearls to your jeweler for re-stringing. A little care will go a long way in making sure your pearls remain lustrous and elegant for a long time.

    Always buy from a reputed jeweler whether you are buying it from a store or via the Internet. Investing in a good quality strand or necklace can be a joy for years and will never go out of fashion.

    Feng shui and Amethyst

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    Feng shui and Amethyst

    by Madhubanti Rudra

    A stone with bright purple hues, amethyst has been a part of Royal adornment and feng shui as an old Chinese discipline always revered for its magical power for bringing luck, health and wealth. When feng shui applies the magical power of amethyst to reduce men’s pains and sufferings, the result is nearly miraculous.

    Feng shui and Amethyst

    Throughout the history, the translucent, purple gemstone called amethyst has been highly praised for its mystical and healing properties. Starting from the ancient Greek to Egyptian mythologies we find the mention of amethyst being hugely used for spiritual and psychic empowerment. In Chinese civilization amethyst remained one of the most used Feng shui tools aimed at clearing negative energy to drive away the hazards from personal or professional life. As such the relation between the knowledge of feng shui and the powers of amethyst is rather close. In order to know the place of amethyst in feng shui, and how this ancient science make use of this well known stone, we have to first learn the basic tenets of feng shui.

    The working of feng shui
    Feng shui is the gift of the ancient land of China to the rest of the world. This thousands years old Chinese practice is founded on the basic tenet of “art of flow”. The science of feng shui which literally means wind and water in Chinese, revolves around the conception of ‘chi’ which is described in the ancient Chinese literature as the universal life force with a ubiquitous presence throughout the environment. Feng shui also emphasizes that everything in the environment is connected with each other and they as a whole create a significant impact and controls the direction of our lives. The whole discipline of feng shui works on the basis of the hypothesis that as water and air purifies and nourishes our biological system, a measured flow of chi ensures a problem free life by cleansing the environment.

    Following are the three main ways of feng shui’s working
    For balancing the chi in environment, feng shui offers a vast assortment of tools and guidelines that rectify the flow of energy through the space. Often described as an art of placement it uses the tricks of rearranging of home décor or architectural corrections to facilitate the free flow of energy through the open spaces of house, workplace or any desired location.

    Symbolism is another important aspect of feng shui remedies. Many objects and imageries of particular shape, size and color are strategically used to tap the energies of five primary natural elements; wood, fire, earth, metal and water that move the chi in desired direction.

    The feng shui is based on the idea that every object in this world is made up of energy. Feng shui emphasizes on the importance of placing the objects in special areas demarcated for particular aspects of lives and thereby create a balance of energy in those areas of life. The crystals are regarded as the most effective energy conductors in feng shui and different crystals are used as different feng shui enhancers.

    Feng shui and amethyst

    The working of feng shui is based on the process of deflecting the negative energy and welcoming the positive energy inside. The crystals’ potential of radiating positive energy is hugely used in the feng shui remedies. Among all crystals, amethyst occupies a special position owing to its versatile healing qualities.

    In the feng shui system, any space like a room, a house, or an institution are divided in a particular way in which each division is called a ‘house’ and each house is assigned a special number ranging from 1 to 9. Each number signifies particular natural symbol and they reflect various aspects of life. If you are in trouble over any issue connected to any of these nine ‘houses’, placing a particular object, according to feng shui will clear the blockage of that area. Now the colorful crystals full of positive energy have the power of repealing negative energy. If you place these crystals in different corners of your house they will resolve the problems related to that particular segment of your home. A stone of many qualities, amethyst connects to most of these segments described in feng shui. Here is an overview of how amethyst can be used to enhance the chi with regard to the particular aspect of your life.

    As for example, the number 1 house symbolizes water and it is related to the journey of life. At the core level this segment is connected with one’s career. Although water colored crystals are main luck enhancer of this area, amethyst can also improve your luck in these matters as well. By increasing the activities of the right side of the brain, amethyst stimulates the intellectual properties of your personality. It also works remarkably for enhancing the concentration level and meditation power. All these naturally boost up your education and career.

    Number 2 symbolizes earth and it is related to relationships. As a traditional sign of self restraint and sobriety placing an amethyst crystal in this corner will inspire the quality of unconditional appreciation of others, thereby improving the relationships in their various aspects.

    Segment number 3 is assigned to the ancestors and symbolized by thunder. This area relates to everything past and everything that yields authority. Placing an amethyst in this area will help one to shake off the mellows relating to the past and help to trace back your spiritual lineage.

    Wind is represented in the number 4 area of the house and is connected with fortunate blessings. The main focus of this area is on prosperity and health. Providing mental peace and reducing stress, an amethyst sharpens your intuitive abilities. Thus placing a piece of amethyst in this corner of the house you can accumulate on health and wealth.

    The centre of your home has been assigned the number 5 and it is the area for reconciliation of all conflicts. Reputed for promoting peace and tranquility, the role of amethyst gets particularly prominent here.

    Area number 6 is the symbol of heaven and associated with the helpful friends. This is the area of your home which connects to the gifts in form of assistance and kindness that we receive from the others and offer to others. Keeping amethyst in this region will help to gain in the numbers of your well wishers.

    Number 7 is the area of lake that represents creative sides of your life. Children are the most important aspect of this area. An amethyst will clear the negative energies from this region and contribute to your child’s physical and mental flourishing.

    The segment 8 symbolizes mountain and it is related to the value of contemplation. This is the area that connects the person to his inner self. This area relates to self understanding and realization of spiritual strength. This area calls for peace and tranquility and the stones capable of bring peace are prescribed for placing in this corner of the house. Amethyst, a traditional stone for spirituality, is advised to be placed here. If someone is suffering from anxieties over self conflicting issues, placing an amethyst in the mountain area of his house will help him to come out of this psychological dilemma. It also helps to gain strength from inside. An amethyst candle holder is a common feng shui accessory that can be used in such situations.

    Number 9 segment represents fire and connects to self esteem and confidence. Although the crystals with bright and reddish hues are generally prescribed for this area, an amethyst also comes to help in resolving issues associated with fulfillment of self. Because an amethyst is capable of making you come to terms with your inner self.

    Health and amethyst

    The above was the description of how you can enhance the various aspects of your life with the strategical placement of amethyst in various corners of your home. There are many more remedies that feng shui has up its sleeve. One among them is battle against many health issues like stress and insomnia.

    Fighting insomnia
    Sleep is the prerequisite for a healthy life, because it is a good night’s sleep which prepares you for the labors of tomorrow. From the feng shui perspective, a bedroom should be free of yang energy that affects the sleeping pattern. The yin energy on the other hand should be cultivated in the bedroom as it is meant to bring rest and relaxation.
    Apart from following the bed room décor in the feng shui way, particular objects are placed in the bedroom to ensure the cultivation of yang energy. Amethyst is one of the most important among them. Amethyst is not only a great tranquilizer, it is an effective absorber of negative energy responsible for a disturbed sleep. These qualities made amethyst the most trusted medium for fighting insomnia. Feng shui prescribes for keeping a piece of amethyst under or beside the pillow to bring back your sleep. It is also believed to induce you into sweet dreams that soothe your nerves.

    Fighting stress
    Our daily routine is a sum total of confrontations and conflicts that creates tension and anxiety. According to feng shui, the mental balance can be restored with a piece of amethyst. It is believed to contain your anger and disharmony with the outer world. The purple ray that it radiates helps to reach out to the spiritual layers of the universe, and heightens your concentration level and meditation power. All these cool you down internally and calms down the tensed nerves.

    Feng shui tools made of amethyst
    There are some special amethyst tools or accessories that are used in feng shui for getting the desired result.

    Amethyst Tree
    Amethyst crystal trees are most widely used feng shui instrument. This beautiful tree is generally set on the base of uncut amethyst. The metal wirings- usually made of gold and sterling silver- are twisted to create the impression of a trunk and branches. The top of the branches are covered with lots of amethyst crystals.

    In our day to day confrontation with the negative forces that intend to block our upward movement, either in career, education or spiritually, we loose our calm and on the process pollute our inside unconsciously. On the other hand if we are surrounded by such objects, that remit positive energy, we are able to feel the sweeter aspects of life and this is precisely the philosophy behind an amethyst crystal tree.

    Amethyst is a powerful crystal for spiritual uplift ment and psychic empowerment. It enhances your intelligence and creative thinking too. That is why amethyst crystal tree is regarded as a very effective feng shui enhancer. The amethyst tree can be placed in the south east region of your home; it will fill your home with peace, harmony and love, by enhancing the natural chi of that area. It also brings wealth and prosperity to your life.

    On the other hand south west corner of your home connects to romance and marital relationship. Placing an amethyst tree in the south west corner of the home will bring love and romance in your marriage.
    It can also help in your career or business, where you often develop discords with your superior or colleagues. As amethyst is believed to inspire harmony and promote contentment, keeping an amethyst tree on the south east direction of your work desk, will alleviate the environment of anger and conflict.

    Amethyst ornaments
    Many people prefer to wear amethyst to get the purple rays of the stone directly. In feng shui treatments, amethyst is often clasped to the body in forms of bracelets and necklaces. By deflecting negativity, the amethyst ornaments protect the wearer from the evil forces and bring emotional balance in a variety of ways. It improves the intellect, memory and thought process. It also enhances the spiritual realization and intuitive abilities. Those suffering under the pressure of stress, constant wearing of amethyst ornaments can calm and sooth them. The body contact with amethyst also improves blood circulation and cures insomniac patients.

    You have to observe certain feng shui procedures for programming the amethyst crystals before starting to wear them on your body. First of all, mix four spoons of sea salt in a bowl full of water and then immerse the crystals into it and leave them for one week; this will purify the stone. After one week take them out of the water and placing them on a ceramic saucer, let them soak in the morning sun light for three hours. In the mean time visualize the picture of the intended result, (like a happy family together, or a sweet relation with your spouse etc). When your visualization is complete, remove the stone from sunlight. Place them on your left palm and cover them with your right palm and once again think of your intention for a while. This completes the charging of your crystals with protective feng shui powers.

    There is another way of the charging and purification of the crystals by holding the crystals over the smoke of incense, contemplating the intended outcome simultaneously. Do not take the crystals too near to the flame as it may change the color of the crystals.

    Amethyst pyramid
    In feng shui ornaments, amethysts are generally pyramid shaped. Pyramids are the reflection of immense energy and physical and will powers of the human beings. In other words they are the culmination of men’s super psychic abilities. A science of symbolism, feng shui aspires to draw this energy into the crystals by giving them this particular shape. As for example the pyramid amethyst pendants are worn to improve the psychic abilities.

    Amethyst balls
    These are also extensively used by those wanting to acquire the secrets of the universe.

    In order to get the talismanic protection from amethyst one can carry them in pockets or purse. They can also be kept under your seat in the work place. A favorite of the Tudor kings and queens, amethyst looks unparallel also as jewellery and ornaments. So an amethyst artifact or a piece of amethyst jewellery makes a unique gift for your loved ones.

    International Colored Gemstone Association – ICA

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    International Colored Gemstone Association – ICA

    by Ashish Dimri

    International colored Gemstone Association has its headquarters in Newyork city; U.S.A. It also has additional bureaus in Idar- Oberstein and Israel. It has over 400 members in 41 countries worldwide.

    International colored Gemstone association (I.C.A.) and its role in gemstone industry

    International Colored Gemstone Association is a non-profit association of international gem traders, gemmologists and people associated in various capacities with this trade. International Colored Gemstone Association has its headquarters in New York City; U.S.A. It also has additional bureaus in Idar- Oberstein and Israel. It has nearly 500 members in 42 countries worldwide. International Colored Gemstones Association (I.C.A.) has members belonging to different fields for example miners, gemstone cutters, jewellery manufacturers, and service providers. It was formed in 1984 when it was felt that there was no association to look after interests of gem trade.

    Its association’s membership represents seventy-five percent of the purchasing power of the international market for colored stones. The main objective of I.C.A. is to unite various segments of colored gem trade. Previously, gem trade had no association to work united. This association made a way for all who work in this lucrative trade. This excellent association stands for excellence and knowledge. Any person who is associated with gemstone industry enjoys patronage and ample guidance from it. In other words, I.C.A. is living ocean of wisdom for the gem trade industry. International Colored Gemstone Association conducts so many functions from conducting tours, congresses and seminars to publishing newsletter to educate its members about latest happenings in the colored gem trade. For example from time to time, it organizes special tours to prominent gem producing countries like Belgium, Colombia, and Brazil for its members. The main purpose of these tours is to inform the various facets of this trade to new and veteran members.

    Some of the prominent activities performed by International Colored Gemstone Industry are

    Congress

    International Colored Gemstone Association often organizes congresses on different issues like promotion and production of gemstones. The main purpose of these congresses is to play link between various segments of gem industry. Here everybody gets an opportunity to discuss various problems and all get a chance to foster business. Mentoring Tours- I.C.A. In addition, plays role of a mentor by organizing tours to various gem producing countries where participants get a rare opportunity to visit places such as advanced laboratories where they are familiarized with modern scientific methods used in trade. They also attend meetings with veteran members of colored gem trade who share business secrets with them. They also visit mining areas to get a first hand knowledge of raw gems.

    Marketing Program

    ICA has recently launched a marketing program through which gemstone and jewellery manufacturers and retailers try to steer and increase demand for colored gemstones in the consumer market. It hopes to gain a lot of experience and profit through this magnificent program.

    Exhibitions

    It also organizes exhibitions of exotic gems and jewellery in international museums. These exhibitions provide ample chance to the visitors to learn about rare gemstones and jewellery. These exhibitions help to develop interest in history of gem trade. From exhibits belonging to past like mogul jewellery to modern age rare collection, one can get to watch these things at these exhibitions.

    Formal Meetings

    It regularly organizes meetings between its representatives and prominent jewelers and gem manufacturers. This is a better way to evolve new and better marketing and publicity strategies for gem trade.

    Educational Seminars

    It regularly organizes a series of educational and discussion seminars that intend to increase colored gemstone perception amongst the local trade. These seminars range from gem export, gem enhancement methods, and new technology. These seminars are helpful as they point out numerous problems and provide their solutions. These educational seminars provide a right platform to share one’s experiences with others.

    Information provider

    Being a collective body of gemmologists, gem cutters, jewelers, and gem enthusiasts; I.C.A. is coffer of valuable information. It informs on supply, demand, innovation and challenges in the colored gemstones business of the 21st century through its publications, forums and tours for all those interested in gem trade.

    Committees

    I.C.A. has set-up many committees to look after various aspects of gem trade. Its various committees oversees many activities associated with trade for example, it gathers data on various issues and provide certification to put in place protocols and standards to be used by the mine operators. There are committees which look after trade policies and technical matters.

    Magazine

    In past, I.C.A. used to publish a two-decade-old IC.A. Gazette providing information about various happenings of the gemstones industry. Now it has revamped it and introduced a new colored magazine, InColor. This magazine contains a cover story, a news section, and two regular feature articles. This new magazine is a mine of information for those associated with the trade. InColor, regularly informs new happenings and future programmes in it.

    International Watchdog

    International Colored Gemstone Association acts as an international watchdog to protect rights of its members. It understands international gem market is evolving day by day and as a result, spurious elements are bringing disrepute to this excellent industry. It informs the prospective buyers and sellers to conform to the standards set by it while doing transaction. As it is an international association therefore its influence is wide spread. Those who need help can contact I.C.A. regarding any complaint.

    Promoter of interests

    I.C.A tries hard to promote business interests of its members. It acts as a facilitator of their business interests. It actively promotes cooperation between various segments of gem trade. In other words it is a dynamic promoter of cooperation on trade and technical matters.

    Advisory role

    From time to time, it advises its members on various trade policies, planning and related programs. Gemmologists and others associated with gem trade can benefit vast amount of knowledge through valuable advices given by I.C.A.

    Friend, Philosopher, and Guide

    It acts as a true friend, philosopher, and guide to its members. It always tries to foster solidarity among various segments of colored stone trade. One could be a gem cutter or jeweler but they feel sense of oneness because of this international association. Being a non-profit association, International Colored Gemstone Association wants prosperity and constant benefits for this lucrative trade and people associated in it. Apart from its commercial activities, it also organizes recreational programmes for its members.

    Pleochroism in gemstones

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    Pleochroism in gemstones

    by Yuman Hussain

    Scientific explanation of pleochronism which is an ability of the stone to absorb different wavelengths of light displaying brilliant colors when viewed from different directions.

    What is Pleochroism

    Have you ever wondered about the color of a gemstone? How and from where different colors originate in a stone? Well, it is through a phenomenon known as Pleochroism, a term with many might not be familiar with.

    Pleochroism is derived from a combination of Greek words-‘pleion’ meaning more and ‘chros’ means color. However it does not mean multi-colored but a change of color in a stone due to movement of light through it. Pleochroism is a general term referred to the processes of dichroism and trichorism. Dichroism is found in uniaxial crystals with single optic axis and trichorism is found in biaxial crystals with two optic axis. When ordinary light falls on uniaxial crystal any given wavelength of light is absorbed except along the optic axis displaying one color in its direction and different color at other angles. These dichronic stones show two colors or shades and trichronic stones with two optic axis shows sometimes three or more shades or colors. The main cause of Pleochroism is due to absorption of particular wavelengths of light. This selective absorption leads to transmitted light, which appears as colored. Two conditions are must for this phenomenon including thickness and crystallographic structure. Secondly the chemical properties of the stone should be strong enough to see the effect.

    Highly visible in doubly refracting colored stones Pleochroism is defined as an optical phenomenon in which light is focused on stone splitting in two different components – ordinary ray and extraordinary ray polarized at perpendicular angle to each other. When different wavelength of light is traveling at different speed following different directions within a stone it gets absorbed producing different colors when it leaves the stone. It makes the stone as if made up of different colors. It is basically an ability of the stone to absorb different wavelengths of light displaying colors when viewed from different directions. These colors depend upon the optical path viewed .This phenomenon can be understood through following example. If all the light except green and blue is absorbed in a crystal then it reflects green color. If a stone absorbs all light except yellow than it will display yellow color. If the stone is observed when turned from first direction to the other then color will change from green to yellow.

    All stones do not show Pleochroism. For example isometric stones such as diamond, garnet, spinel and halite do not show change in color as they have same structure having same light absorbing capacities preventing light waves vibrating in different directions. Almost all transparent minerals show Pleochroism. Most of the dichronic stones are hexagonal, Trigonal or tetragonal with one structural direction along the major symmetry axis whereas trichronic stones are orthorhombic, monoclinic or triclinic with three axis of symmetry or direction that can absorb light.

    Sometimes in order to display color or to make it more attractive stones are cut in such a way to show Pleochroism or to hide it. An important tool for mineral identification it is required to examine the stones displaying different pleochronic color schemes. When we use plane-polarized light under microscope a pleochroic stone changes its color. Many stones are pleochronic but sometimes color change is so negligent that it require optical instrument for detection. Some gemstones show stunning color displays. Often color change is restricted to shade changes for example from light purple to dark purple or violet. Pleochroism is strong when color change is distinct and it is said to be weak when there is only minor color change in a stone. An individual transparent crystal can show the display of Pleochroism.

    Pleochroism is observed:
    – If there is change in actual color that is, if a stone is seen blue or red from different positions.
    – If there is change in the intensity of color that is if a stone becomes light to dark in shade.

    Tourmaline is a dichronic substance reflecting two colors in which ordinary ray is absorbed and extraordinary ray is transmitted. Cordierite crystal show trichorism when light passes through parallel to three crystal axis violet, yellow or blue light is absorbed. When crystal is cut the axis edges show mixed colors of blue, yellow, violet and yellow, violet and blue. Tanzanite is also another popular diachronic stone in which there is selective absorption of different lights displaying brilliant colors ranging from blue to purple when seen from different light sources. Blue Aquamarine sometimes might show a slight color change from pink to green if viewed from different directions. Fluorpatite is a diachronic yellow mineral which turns blue when it is viewed along its axis. There are some other stones which show best examples of Pleochroism. These are:

    • Andalusite which show change in color yellow green to red brown.
    • Zoisite which show colors from pink to yellow.
    • Kunzite which show colors from pale pink to dark pink.
    • Iolite which show colors from blue to purple.
    • Corundum which shows color from violet to orange.
    • Alexandrite which colors from red purple to orange to dark green.
    • Peridot which shows colors from yellow green to green.
    • Beryl which shows color violet to being colorless.
    • Elbanite which shows pale color to dark color.
    • Carletonite which shows blue color to being colorless.

    A spherical shell of color, pleochroic halo is present around radioactive impurity in a stone. This ring or halo said to represent a site where crystal structure has got changed by the absorption of energy of radioactive alpha particles .As energy has got absorbed it produces an intense color centre on the inclusion with in a stone. These pleochroic halos are common in zircon, monazite, xenotime and apatite. The rings are distanced and identified according to the range of alpha particles with in a stone.

    The beauty of a stone is enhanced when it display different colors from different angles. So next time while buying a gemstone do not forget to look at the kind of light displayed at the stone.

    Asterism in Gems

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    Asterism in Gems

    by Nasrina Parvin Khan

    “Asterism” is an exclusive light effect (which we called special optical phenomenon) of some crystal. When light pass through these crystals, its exhibit a star-shaped figure, which called “asterism”.

    Asterism

    Asterism” is a term, which is most commonly used in gemology. It refers a kind of special optic phenomenon that has been seen in several gems.

    Special optic phenomena refer uncommon and excellent optic properties exhibit by some rare gemstone. The phenomena are particular property of transmitting or reflecting light. The structure or inclusions of a mineral in gems is the reason of this property. The beauty and value of gems depend on their optical properties.

    “Asterism”-one of the important optical phenomena has been seen in sapphires, rubies, rose quartz and some other gems. The term “Asterism” came from the Greek word “aster”, which means star. From the name we can guess “asterism” is star-shaped light effect across the surface of gems.

    Special optical phenomenon

    “Asterism” is an exclusive light effect (which we called special optical phenomenon) of some crystal. When light pass through these crystals, its exhibit a star-shaped figure, which called “asterism”. This figure is produced by reflected or transmitted light.

    Asterism in Gems

    Gems, which show an illuminated star, just bellow the surface of crystal called star gems. The most popular star gems are star ruby and star sapphire. Other gems, which also possess the special optic phenomenon “asterism”, are rose quartz, garnet, spinel, Chrysoberyl and Diopside. There are a few specimen of rock crystal, which has the phenomenon.

    The star in the star gems may have four to twelve rays depending on the crystal system of the gems. But the six- rayed star effect is most common. Usually, six-rayed star show by the star rubies and star sapphires. Sometimes these star gems exhibit the twelve-rayed star effect. But the twelve-rayed star effect in corundum is occasional. Rose quartz exhibits six-rayed star. Some garnets and spinel commonly have the star effect with four rays, but these star gems can show six-rayed star effect if cut in a distinct way. Some crystals like Chrysoberyl and Diopside only exhibit four-rayed star effect.

    “Asterism” is caused by the dense inclusions of tiny fibres of foreign minerals in gems. Generally, these inclusions are the reason of the reflection of light and form a wavy star like formation, which moves around when the mineral is rotated. All the inclusions in the gems are formed via exsolution.

    The inclusions must be long, very thin needle like which called as rutile. “Asterism” is produced when needles intersect each other in multiple groups. Small needles of rutile (titanium oxide), sometimes called “silk” are oriented inside the minerals in the direction of the crystal growth system. There is a relationship between the gem’s growth and the number of rays produced by the reflected light.

    There must be three or more chatoyant bands inside the gems to produce “asterism”. The arrangement of needles in a hexagonal pattern produced six-rayed “asterism”.

    Exsolved inclusions form a pattern in the host mineral. The pattern may vary from mineral to mineral, but in case of specific mineral the pattern remain same. In case of corundum, we can see rutile is exsolved in three directions crossing at 60 degree or 120 degree in the basal and produce six or twelve-rayed star. When the rutiles crossed at 90 degree, it produces a four-rayed star. Star gems are translucent to opaque .The rays of star should cross at the top of these gems and be distinct.

    star sapphire

    Star Sapphire

    The sharpness and the size of “asterism” in gems, which identified as phenomenon, depend on the quality and quantity of rutile needles. Small to smaller size of rutile needles help “asterism” to be sharper. When the needles are visible with open eyes as inclusions, the gems turned into a low translucent stone and lack “asterism”.

    Large quantities of rutile needles in a crystal produce phenomenal “aster”. If the quantities of rutiles are small, “Asterism” is visible in only a small area. These gems are not recognized as phenomenal gems .The clarity of these gems can be improve by dissolving some rutile needles with heat treatment. Heat treatment allows various elements to be incorporated into crystal. Then rutile needles form by very gradual cooling system and induce “asterism”.

    Inclusions are not present in all star gems. Some specimens leave holes or empty areas in the host. Reflection creates from fibres or fibrous cavity in the crystal.

    Types of asterism

    There are two types of “asterism”, like Epiasterism and Diasterism. Epiasterism is creates by the reflection of light on parallel-arranged inclusions inside the crystal. Diasterism is creates by the transmitting light through the stone, mostly seen in rose quartz. To see this effect a lighted background is essential.

    To display the star effect in best way a gem is cut as cabochon with the girdle parallel to the needles. The domed stones are round or oval shaped.

    The special optical phenomenon “asterism” is most visible in direct, single pointed light source, like an incandescent bulb, fibre optic light, and penlight or in sunlight.

    The distinctiveness of the star and degree of strait ness of each ray help to judge the quality and value of star gems.

    More Resources:
    Asterism in gemology
    Asterism pictures
    Asterism in quartz