Aquamarine Identification

by Erum Qureshi

Aquamarines, belonging to the Beryl family, are relatively easy to identify. Various simple tests can reveal the authenticity of an aquamarine stone.

Summary: Aquamarines, belonging to the Beryl family, are relatively easy to identify. Various simple tests can reveal the authenticity of an aquamarine stone.

Aquamarine – This name is derived from a Latin word, which means water of the sea and so named because of its seawater color.

Most gems have a bluish green color, which was highly prized at one time but has lost its charm lately. There are also clear green Beryls, which are colored by iron instead of the chromium colored emeralds and have a light, clear color, quite unlike the deep green of emerald. The other is the colorless variety, which is named Goshenite (after Goshen County in Hampshire County, Massachusetts). This name, however, is fast becoming redundant, and the name colorless beryl or white beryl is commonly used.

Species

Aquamarine belongs to the species beryl. Beryl is a silicate mineral having chemical formula Be3Al2 (SiO3) 6. Beryl of non-gem quality is mined as the raw material for beryllium, which is now increasingly used in industry. Aquamarine crystals are hexagonal and further, many of them exhibit a tapering form due to erosion.

Hardness

The hardness of aquamarine is 7.5 on the Moh’s scale. Like all Beryls, an aquamarine has a weak basal cleavage and a tendency to brittleness.

Determination of Specific Gravity (SG)

The SG of aquamarine lies between the range of 2.66 and 2.80. Some Madagascan stones have higher densities owing to a trace of alkali metal in their composition. The specific gravity or SG is measured by immersing the stone serially in a set of high-density liquids.

These liquids come in a set of three or five liquids of varying densities. They work on the simple premise that if a stone of lesser density is immersed it will float, that of higher density shall sink and one of equal density will remain suspended.

Refractive Index

The refractive indices for aquamarine vary from 1.572 to 1.590 for ordinary ray and 1.567 to 1.583 for the extraordinary ray.

The refractive index or RI is measured by placing the stone face down with a drop of contact liquid between the polished face of the gem and the glass of the Refractometer. The light rays leaving one medium (air) and entering another obliquely (the stone) will seem to bend a little at the place of contact. This is called refraction of light and the reading is taken herewith.

Pleochroism

Aquamarines exhibit a distinct Dichroism that is the ‘twin colors’, the strength of which depends on the depth of color of the stone – they are deep blue and colorless, the extraordinary ray giving the attractive blue color. The birefringence (difference between the highest and lowest refractive indices) is negative in sign and 0.005 for the lower indices and rises to 0.007 to 0.008 for the stones with higher indices.

Absorption Spectra

When the aquamarine is viewed through a spectroscope, the absorption spectrum it shows (ascribed to iron and not very pronounced) there is a broad band in the violet at 427 nm and a feeble diffuse band in the blue-violet at 456nm. Further, the extraordinary ray, which can be isolated by the use of a Polaroid disc, shows these bands more strongly, and in such conditions a narrow and delicate absorption in the middle green can be observed at 537nm.

Fluorescence

Aquamarine does not exhibit luminescence. All colorless Beryls, like the blue and sea-green stones show a strong greenish-blue color when viewed through the Chelsea filter. In this way, aquamarines can be picked out from a parcel of similar looking stones.

Treatment and look-alikes

Practically all the beautiful blue aquamarines seen in jewelry are greenish-yellow (or even brownish-yellow) stones, which have been heat-treated. The blue color is induced by heating to a temperature between 250 and 720 degree Celsius for a varying period. The resulting color is permanent.

The most effective imitation of the aquamarine is the synthetic spinel colored pale blue by cobalt. These synthetics will have a totally different refractive index (1.782) and SG (3.63) from aquamarine. Gemologists identify these synthetics by placing the suspected stone close to a strong light and viewing it through a Chelsea Filter held close to the eye. The synthetic spinel shows a distinct red under the filter, whereas aquamarine shows a decided green.

Jewellers Loupe

by Ritika Changrani

A jeweller’s loupe is a tool that helps identify the internal flaws, cracks and blemishes on the surface and any other cover ups on the gemstone.

A Loupe is just a magnifying glass. It helps to see the magnified image of gemstone and serves as the identification and grading tool. A Loupe is made of a powerful convex lens. Through a jeweller’s loupe, one can easily see the internal flaws, cracks and blemishes on the surface and any other cover ups on the gemstone. Jeweller’s loupe is the most important test equipment for testing gemstones.

How to Choose a Jeweller’s Loupe?

There are two important factors to be considered while choosing the right jeweller’s loupe. They are the size and magnification of the lens and the optical quality. Loupes are available in different sizes and powers. The standard size used for testing gemstones is of 18mm length with 10X, which magnifies the gemstone to ten times its size. The jeweller’s loupe is available in 20X and 30X, but they are not much used.

The jeweller’s loupe has to be tested for achromatic and spherical aberrations. Chromatic aberration refers to colour fringes of the image due to dispersion caused inside the glass lens. The loupes which are corrected from chromatic aberration are known as achromatic. Spherical aberration refers to the distortion caused due to the differences in refraction on the outer edges of the lens and the rays traveling through the center. The loupes which are corrected for spherical aberration are termed as ‘aplanatic’.

While choosing a jeweller’s loupe it is necessary to check that they are achromatic and aplanatic to get accurate results. In a better quality jeweller’s loupe, three lenses (known as triplet loupe) are used so that the field of vision is in focus to the edges and no false colour is imparted to the eye. The use of three lenses eliminates the pin cushion distortions and chromatic and spherical aberrations.

While selecting a jeweller’s loupe you can easily identify if they are achromatic and aplanatic. Look at the white light through the loupe. If the white light remains white without changing the colour, the lens is corrected for chromatic aberration. Similarly spherical aberration can be tested by looking at the mm squared drawing paper. If they remain squares when looking through the loupe, the loupe is aplanatic.

It is also better to choose a loupe with black framing around the lens, since this avoids reflections which may alter the color of the object under view. Do not opt for golden or other bright coloured frames since they interfere with the colours.

How Does a Jeweller’s Loupe Work?

Jeweller’s Loupe magnifies the image of the stone under test as per its magnification power. Suppose, we are using a 10x loupe, the image is magnified to ten times its original size. This helps us clearly see the flaws, cracks and other distortions in the stone. A triplet loupe consists of one ‘plano-convex lens’, one bi-concave lens and one bi-convex lens. The ‘plano-convex lens‘ is used to eliminate spherical aberration and the other two are used to eliminate chromatic aberration. Depending on the observations, the nature of the gemstone can be detected. Jeweller’s loupe helps to detect diamonds, sapphire, alexandrite, ruby, pearls and many other gems.

How to Use a Jeweller’s Loupe

• Remove your spectacles if you are wearing one. Unfold the jeweller’s loupe.
• Hold the jeweller’s loupe between the thumb and the index finger. Keep the jeweller’s loupe as close to the eye as possible without touching the eyeball. The loupe should be so close that your eyelashes almost brush through it. Once the loupe is close to your eye, see that it is kept stationary by letting the back of the thumb rest against the side of the nose. Keep the remaining three fingers in parallel or just below the index finger. Keep both your eyes open to avoid eye straining.
• Make sure there’s enough light in the place where you are observing the gemstone. Fluorescent and other light bulbs lack some colours which are necessary. Hence sunlight is the best light for the testing gemstone. Diamond lamps can also be used.
• Place a clean white soft cloth on the surface you are using. This helps to avoid scratches on the gemstone and also avoids rolling down in case it slips down. Next, place the stone at a distance of an inch or a little more on the other side of the gem loupe. Peering through the gem loupe, move the stone to and fro until it comes in focus. Keep moving the stone front and back and turn the stone in different directions until the area of the stone is seen with sharp focus.
• Note the external and internal features of gemstones. Look if there is unevenness in colour. If there is unevenness in colour, there is a possibility that the gemstone is dyed or painted to imitate a high quality gem. Many deceptions which cannot appear to the naked eye can be observed through the jeweller’s loupe. If you already have some real gems of similar types, you can observe both and compare them.
• Some of the things you should observe while testing the gemstone through the loupe are :
  • Symmetry: Check if the gemstone has a balanced symmetry
  • Number of facets: Observe whether the gemstone has the right number of facets required for the particular cut
  • Sharpness of the facet edges: Hard stones have sharp edges while synthetic stones have soft edges
  • Inclusions, flaws and bubbles in gemstones: Inclusions, if present, don’t necessarily indicate that the gemstone is bad. Instead, the gemstone can be a natural gem. Flaws in gemstones are not an indication that the gemstone is of low value. Bubbles in gemstone indicate that the gemstone is synthetic.
  • Scratches and cracks in gemstone: Soft stones tend to scratch easily while hard stones crack.

Gemstone Mining Methods

by Sheweta Dhanuka

Gemstones are treasured by most of us and to retrieve these precious gems from deep down the earth crust one has to go in for treasure hunt. Gemstone Mining is very complex and tedious process that requires huge input of valuable resources such as time, workforce, equipments and knowledge etc. There are different methods for recovering the gemstone from the lap of Mother Nature. The appropriate procedure is selected depending upon the circumstances but no matter what method is selected the entire process of gemstone mining needs to be very systematic as it costs a lot of money. The total process of gemstone mining is so intricate that inspite of putting in so much efforts there is no surety of the results. Failures and disappointments always have higher percentage than the success.

In order to attain the positive results, the first and foremost requirement of this exclusive process is to identify the gemstone deposits. This necessitates the vast knowledge of gemstone properties, with the help of this key the deposits are identified where there could be the probability of the finding the precious and semi precious gems. The route of gemstone mining is executed all the way through highly developed and technical system. But we all know, traditional methods have there own uniqueness that cannot be denied even after developing new scientific methods. All the methods are categorized into two types of mining viz. surface mining and underground mining. First always the surface mining is done and then when fruitful results are not achieved underground mining is brought into action. Underground mining is always more expensive because –

• It takes long working hours.
• For underground mining more advanced equipments are required.
• There are extra costs incurred for activities such as pumping, electricity, digging etc.

Surface Mining

Surface Mining is done to obtain gemstones from the rocks near to the surface of the land. There are six different types in which surface mining could be done. The miner decides on surface mining technique depending up the overall cost and time. These methods are:

[1] Hydraulic Mining

In this method powerful jets of water is used to loosen the gem material from the overburden. The miners make channels on the rock/gravel hillsides in form of sluices where water under pressure is sprayed. The water pressure splits down the rock and washes large rock piece of it downhill. And finally the gems as raw stones are separated. This mining is very harmful for the environment as it wrecks the mountains and blocks the rivers. Hydraulic surface mining was found way back in 1800s and continued till 1960s but now it is stopped completely due to its disastrous consequences to the natural beauty.

[2] River Panning

River Panning is the method where gemstones are collected while washing the gravels from a river/stream in the mining area. It is also known as placer mining. This method is initiated with the identification of the gravel which may contain gems. The best place to find the gravel deposits is in obvious gemstone producing rivers, streams and creeks. Then a large pan is filled with water and shaking it back and forth to settle the heavy material to the bottom of the pan. The lighter material is washed over the top of the pan and larger rocks & pebbles are removed by scooping them over the edge. These steps are repeated until there is only about a tablespoon or two of concentrates left in the pan. Nearly all panning is completed using the riffles in the pan.

The left over concentrated is then shifted to a smaller clean pan. Drop of liquid soap is added to keep the tiny chips from “floating.” The less weighty material shall float down with the water and the gems, in case the gems are there, it shall stick and stay at the upper end of the pan. This is a very time consuming method and the chances of success are very less.

[3] Open Pit Mining

This mining can only be accomplished under the guidance of an experienced Gemologist. First he scrutinizes the location to be mined with respect to value of the rock and minerals below the surface, cost of digging the mine and the after effects of mining on the environment. The monetary value of rocks and minerals keeps appreciating over the years so once it is profitable to mine then only open pit mining is done.

Once the location is finalized, layers of the land are removed one after the other till rocks are visible. Then the rocks are removed and gems are searched for in the rocks and sent for further processing. Sometimes explosives like dynamite are used to reach deeper and deeper to recover the required rock possessing the gems. After the mining is done, the area turns into pit which is used as landfill. Landfill is huge open space used for dumping the garbage. Once it is fill it is covered the layer of mud. Finally when the trash decomposes in long run and land can be again used for some other purpose apart from mining. This mining method is relatively easy and cost effective. However, it is performed only when rocks are near to the surface of the land.

[4] Strip Mining

This process is very similar to open pit mining. The mining site is identified; the trees and bushes are removed with the help of the bulldozer. The remains are dumped at the nearby area. Many small-small holes are drilled distant from one another through the rock. Dynamite are placed inside these holes and blasted to get the rocks with gemstones. Raw stones then are sent for further processing. This mining is done in long strips so it is called as strip mining. Once the first strip is completed, the second strip starts. The dirt obtained in making the second strip is dumped in the first strip. Similarly it goes on till the entire site is worked on. And in the last strip the remains of the first strip is filled in. The top layer is of mud that is leveled on all the strips together making the land ready of re-use.

[5] Mountaintop Removal Mining

In this mining method, the mountain top at the ground level is cleaned by cutting the trees and shrubs. Then using the dynamite the top of the mountain is blasted for making the vein. This gives huge blocks of rocks from which the gemstone in unprocessed form are retrieved. The dirt obtained after the blast is dumped into the valleys with the help of bull dozers and trucks.

[6] Quarrying

This mining method is quite less hazardous to the environment. The rock attained from this mining is used for making buildings. Therefore, the way quarrying is to be done depends upon the purpose of re-use of rock. The rocks are drilled to use the left over for cement, it is blasted with dynamite to use the rocks for the interiors of the house like flooring, kitchen slabs. In any of the method after getting the rock the gemstones are searched and then the rocks are spared for re-use.

Underground Mining

Underground mining is done when surface mining is not possible or does not yield rewarding results. Moreover, precious gemstones are mostly found through underground mining. In the method the miners make underground rooms where they further dig the ground more and deeper. Underground mining is done in numerous ways. These are –

[1] Borehole Mining

As the name suggests holes are drilled very deep inside the plain land. In these holes a long huge tube (having enough space to allow the water to pass through) is dropped. Then water is pushed down the tubes with the force, the water hits the rock and breaks it down. The water combines with the rocks, dirt and mud to make slurry. This mixture is pumped back from the tubes and stored into tanks. The unwanted water is thrown out the left over rocks are processed for gems. This method is very much environment friendly and the shifting from one place to another is quite easy.

[2] Drift Mining

This mining is done on the mountain sides. Rock are identified which are on the sides of the mountain. The opening is made below the identified rock. These opening are made horizontally and are known as tunnels/drifts. From the drifts the desired materials are retrieved as due to gravity the material comes down the hill easily. This is one of the cheapest gemstone mining methods and gives good results as well.

[3] Shaft Mining

In this method, vertical tunnels are created below the mountains and through the lift miners moves up and down the mines. The vertical tunnels are called as shafts. Two shafts are created. One is used for the movement of the miners inside the shafts and the other shaft for brining the material on the ground. From the man shaft, small tunnels are made that reaches the rocks possessing the gems. These small tunnels are used for blasting and when the rocks breaks into small chunks those are brought up on the ground through the second shaft. After the work is finished the mines are closed by refilling the shafts with dirt, mud, pebbles and cement etc. This is quite a costly method.

[4] Slope Mining

Slope mining too has shafts but these shafts are first made slant and then parallel to the ground. Usually, this mining is done when it is not possible to make the straight shafts therefore it is named as slope mining. The tunnels are not very deep in the gemstone mining method. Using the conveyor the broken are rocks are brought out.

[5] Hard Rock Mining

Same as drift mining, tunnels are made inside the grounds instead of mountains. First a small opening is made which is referred as Adit. Later, using Adit, tunnels are made vertically deep down the ground using explosives like dynamite. The tunnels are called as shafts. Like wise many shafts are made and each one has a different function. For examples – one could be used for miners going inside and coming back to the ground, second for air ventilation and so on. At the end of the shaft, there one more shaft is made that leads to the rock that contains gemstones. Deep inside the earth crust many different floors are created and one floor after the other is completed. This is the most dangerous gemstone mining method and therefore is brought into practice quite less.

In all the mining methods the rocks are broken into medium or small chunks using the explosives such as dynamite. The broken rocks are then sent to the other processing plant where the gemstones are obtained in the form of raw stone. These raw stone reach to the next level of gemstone processing that involves cleaning, cutting and polishing etc. The gemstone that finally gets mounted to the awesome jewelry pieces, from the scratch passes through the numerous steps that involve the sweat of many people.

It is very easy and classy to wear the gemstone jewelry but the amount of hard work involved in obtaining these precious and semi-precious gemstones through the mining methods is immense. Gemstone mining methods are certainly mind-numbing and it is an exclusive proficiency of finding inimitable raw stones from mines that are crafted into amazing gemstone jewelry!!

Diamond Marketing by De Beers

by Erum Qureshi

That ‘a diamond is forever’ is the probably the world’s greatest, most expensive and widely circulated PR scam! The on-going, century-long campaign by diamond giant De Beers owned by the Oppenheimer family began in 1938; De Beers needed a slogan for diamonds that expressed both the theme of romance and everlasting love.

The on-going, century-long campaign by diamond giant De Beers owned by the Oppenheimer family began in 1938; De Beers needed a slogan for diamonds that expressed both the theme of romance and everlasting love.

Consequently, N.W Ayer, De Beers’ New York based ad agency, came up with the line ‘A diamond is forever’. Even though diamonds can be shattered, chipped, discolored or reduced to ash, the concept of eternity perfectly captured the magical qualities their client wanted to attribute to their product. The campaign began in America and projected the diamond onto the man-woman relationship, subtly altering the public’s view of the way a man courts, and wins a woman. That it was forever also aimed to associate the stone with a sentiment that inhibited the public from ever reselling it. Ask anyone who has tried reselling their diamonds, and they will tell you how it is practically impossible to even recover a diamond’s cost price, let alone make a profit on that investment.

De Beers controls over 60% of the world’s diamond market; it has stockpiles of the stones and sets the price on them. However, this invention was more than just a monopoly for fixing diamond prices, it was a strategy formulated for De Beers by N.W Ayer in America and later followed by J. Walter Thompson in the rest of the world for converting carbon crystals into globally accepted icons of wealth, romance and power.

The diamond ring was pitched not as a marketable product but as a symbol of everlasting love and security and an inseparable part of courtship and marital bliss. There was no direct sale to be made, no brand name to be impressed on the public, just the idea of eternal emotional value surrounding the diamond. The pitch succeeded. And how! Except for those few stones that have been destroyed, every gem quality diamond that has ever been cut and polished still exists today.

Kimberly diamond mine, owned by De Beers group

Nearly a hundred million women wear diamonds, while millions of others keep them in vaults and safe-deposit boxes as family heirlooms. The public holds an estimated 500 million carats of gem quality diamonds (more than fifty times the annual production of gem quality diamonds in any given year by De Beers). If a significant section of the public ever decided to put these diamonds up for sale in the market, the price so carefully controlled and sustained by De Beers could never be maintained. For the diamond invention to survive, for De Beers itself to survive, these hundred million women had to be stopped from ever parting with their diamonds.

It was the symbolism, not the value. The idea that diamonds are a gift of love: the larger and finer the diamond, the greater the expression of love. Men are aware of the symbolism value, which is why they have to buy a diamond ring even if they know it’s a creation of the De Beers monopoly. De Beers spent millions to ingrain in the minds of everyone that they have to shell out thousands for the diamond if a man wants to marry his woman. It was how one could make ‘two months’ salary last forever’!

De Beers sent representatives to high schools across the country to teach young girls about the value of diamonds and feed them romantic dreams. Word was spread by diamonds worn by Hollywood stars, British Royalty and wives and daughters of political leaders and celebrities, by women who could make the common man’s wife or girlfriend say ‘I wish I had what she has’. Love began to be measured in carats.

In the 1960’s diamonds were discovered in Siberia and De Beers saw its control-supply chain monopoly being threatened. It closed a secret deal with the Soviets to market these small stones and the marketing campaign for ‘eternity anniversary rings’ was launched, targeting an entirely new market of older married women.

Perhaps the biggest controversy De Beers ever faced was that of Conflict Diamonds. Although the industry has started following the Kimberly process (wherein a diamond is monitored and certified at every point of its production process), not very long ago De Beers was still buying Angolan diamonds and insisting that tracking stones was unfeasible. No ad campaign for De Beers ever highlighted the fact that mining undertaken in African countries violate innumerable human rights. In these mines, small children are made to dig in small underground pits, where men and women can’t fit, even though child labor is illegal.

Workers and communities in and around mines suffer due to state orchestrated repression, toxic run-off from unsafe mining practices, tuberculosis, HIV infections, prostitution, immune disorders, racial discrimination and slavery. In the past decade, millions of people have been dispossessed of their livelihoods, land, future and their lives in places like Katanga, Congo and Zaire where De Beers has its mining operations. Such topics are off the agenda for De Beers, the media and the women who choose to wear these diamonds. For them, it serves to 1) Reassure them that a man values them,
2) Reassures them that he is financially stable, and
3) Draws respect from other women because of Nos. 1 and 2.

The question why the people from the world’s richest mining metropolises are also one of the world’s poorest and most downtrodden does not occur to anyone.

Back home in India where 80 % of the world’s diamonds are cut, children are given the smallest stones to work on because their eyes and fingers are better suited for shaping the tiny facets. These children suffer from eyestrain, repetitive motion injuries and lacerated lungs from diamond dust. Skilled laborers in India earn less than 1/5th of what their counterparts in Europe or America do. Where is the romance in that?

Today, being faced with increased competition, the threat of synthetic diamonds and newly discovered diamond reserves, De Beers has decided to stop buying the world’s surplus diamonds as it has been doing all these decades to control supply. It markets itself as a clean diamond company, guaranteeing bloodless stones because it lies in its best commercial interests to do so. It would even suit De Beers if the supply of African diamonds somehow dried up; they could then get rid of its $4bn stockpile of accumulated carbon. As always, exploiters minimize the awareness of the resources they target, laying emphasis instead on the glamour and lure of the product they market.

Differentiating Diamond and its Imitation

by Erum Qureshi

There are various decisive tests to assess the authenticity of a diamond. The Ceres Diamond probe, Rayner Diamond Tester, Diamond Pen are a few popular instruments.

The unique hardness of diamond enables it to scratch the polished surface of synthetic corundum and no other substance on earth can do this. However, using hardness as a test is considered crude and seldom necessary since the diamond itself may suffer some damage in doing so.

The most notable diamond Simulants are synthetic cubic zirconia, synthetic strontium titanate, YAG (yttrium aluminium garnet) and GGG (gadolinium gallium garnet).

Synthetic white spinel, made from the Verneuil flame-fusion process is also used as a substitute for small diamonds in multiple gem settings; moreover, it is singly refractive. But it gives a Refractometer reading of 1.726, has a low degree of fire, and measures 8 on Moh’s scale of hardness. Synthetic rutile has six times the dispersion of diamond but is easily recognizable because of its high refractive indices and a large double refraction. YAG (yttrium Aluminium garnet) has the appearance of having properties of a diamond Simulants, and is differentiated from diamond by the Immersion Contrast method.

Danger of confusion between diamond and its simulants became much more apparent when Cubic Zirconia appeared on the market.

There was a demand for developing special apparatus that would make the distinction between diamond and its Simulants rapid and certain, even in the case of mounted stones and with a very rudimentary knowledge of gemology. The most ingenious and effective method of differentiating diamond from all other gemstones makes use of its outstanding property as a thermal conductor, which is higher than for any other substance – higher than even copper or silver.

The Ceres Diamond probe was the first to exploit this property even with small specimens and in the case of mounted stones. The Ceres probe has two thermistors and a small copper tip in a convenient holder. When the instrument is switched on, the tip of the probe warms up. When it is gently held to the surface of the stone to be tested, the needle of the instrument swings to the right and a green light flashes in case of a diamond. With any other stone, the needle of the meter swings to the left and a red light flashes. The probe of the Ceres instrument is very delicate and needs handling with care, but even very small stones can be tested with it.

Another instrument of the same kind is the British made Rayner Diamond Tester. Such equipment is very costly but to anyone dealing with diamond jewelry, this is a relatively small matter when compared with the value of the goods tested.

The GIA has made use of another property of diamond to differentiate it from simulants. This particular property is the diamond’s affinity for grease or greasy liquids. The Gemological Institute of America has produced a Diamond Pen, charged with a specially prepared liquid, which left a visible mark when drawn across the table facet of a diamond, but which broke up into droplets on the surface of all other stones.

Another test for singling out a diamond simulant is the Immersion Contrast method. When light is placed over stones (Strontium titanate, YAG, GGG and CZ) immersed in di-iodomethane (methylene iodide; a high density liquid with a refractive index of 1.742) or Refractometer contact fluid (RI 1.81) different stones show differing patterns. All except strontium titanate show a dark ring diminishing in width as their refractive index approaches near to that of the liquid. This is a definite visual indication of differentiation between diamond and its simulant.

Another diamond simulant, though very rare, is a diamond doublet. The top half (crown) of this consists of a diamond, which is cemented on to a pavilion of some other colorless stone. When such a stone is viewed obliquely through the table facet, a shadow of the edges of the facet can be seen on the underlying cement layer, revealing the fake.

Another way to differentiate between a diamond and its simulant is ultra violet radiation. Under long-wave ultra-violet light, diamonds will show a very varied degree of fluorescence. If all the ‘diamonds’ in a multi-stone setting show a similar fluorescence, they are certainly not diamonds. Under X-rays, almost all diamonds show a blue fluorescence and a brief exposure on film will show diamonds to be far more transparent to X-rays than any other stone. This technique is worth practicing as it is a decisive test.

Fake Gemstone names

by Mark

List of Fake and false gemstone names and its Preferred Gemological Names.

World Famous Gemstones

by Mark

Stunning gallery of few world famous gemstones pictures, Just flip through the images to see the next one.

The Guinness Emerald Crystal

The 1759-carat Guinness Emerald Crystal. The stone was found at the Coscuez in Columbia and is one of the largest gem-quality emerald crystals in the world

The Logan Sapphire Brooch

422.99-carat Logan Sapphire from Sri Lanka. It is the heaviest mounted gem in the National Gem Collection, and is framed in a brooch setting surrounded by twenty round brilliant-cut diamonds, totalling 16 carats.

The Mackay Emerald Necklace

The largest cut emerald in the National Gem Collection designed by Cartier Inc. In 1931, Clarence H. Mackay presented the necklace as a wedding gift to his wife, Anna Case

The Mandalay Ruby

Origin unknown, Mandalay Ruby is one of the largest fine rubies in the world

The Maria Alexandrovna Sapphire Brooch

260.37 carats, Russian Emperor Alexander II presented this to his wife, Empress Maria Alexandrovna.

Lindsay Uncut Topaz

On the left side The Lindsay Uncut Topaz, weighing 70 lbs, right side: The Freeman Uncut Topaz, weighng 111 lbs. Center: The American Golden Topaz

The American Golden Topaz

Weight: 22,892.50 carats, largest cut yellow topaz in the world, and one of the largest faceted gems in the world.

The Bismark Sapphire Necklace

98.6-carat deep blue sapphire in a diamond and platinum necklace.

The Chalk Emerald Ring

37.82-carat Chalk Emerald ranks amoung the very finest Columbian emeralds, it was once the centerpiece of an emerald and diamond necklace belonging to a maharani of the former state of Baroda in India.

The Delong Star Ruby

The Delong Star Ruby resides in the Natural History Museum in New York City. It weighs 100.32 carats.

The Gordon Sapphire Necklace

This piece belonged to Aron Gordon, the founder of Gordon Jewelers. Here is what Sotheby’s had to say about the piece: “The pendant set with an emerald-cut sapphire weighing approximately 50.00 carats, within a clustered frame set with 10 marquise-shaped, 26 pear-shaped, 7 round and 25 baguette diamonds weighing approximately 14.50 carats, the necklace set with 51 round, 56 marquise-shaped and 4 pear-shaped diamonds weighing a total of approximately 22.50 carats, mounted in platinum, length 17 inches, pendant detaches, may be worn separately as a brooch. Estimate: $50,000 to $70,000.

The Gordon Star Sapphire

52.00 carats, framed by 24 pear-shaped diamonds weighing approximately 6.60 carats, mounted in platinum, ring shank detachable, retractable pendant loop.

The Midnight Star Ruby

116.75-carat deep purplish-red star ruby is part of the New York Museum of Natural History’s collection.

The Mogok Ruby

Alan Caplan Ruby or the Mogok Ruby is 15.97-carat untreated Burmese stone, Sultan of Brunei gifted this as an engagement ring for one of his wives.

The Patricia Emerald Crystal

It is one of the largest gem-quality emeralds in the world, The stone resides in the New York Museum of Natural History.

Queen Marie of Romania’s Sapphire

A cushion-shaped sapphire weighing 478.68 carats, King Ferdinand of Romania purchased this for Queen Marie.

The Ruspoli Sapphire Crystal

133.06 carats sapphire, Paris Museum of Natural History.

The Star of Bombay

The 182-carat Star of Bombay sapphire is from Sri Lanka. It was given to silent film star Mary Pickford by her husband, Douglas Fairbanks Sr, currently at Smithsonian Institute.

The Stuart Sapphire

The stone was set in Queen Victoria’s State Crown, on the front just below the Black Prince’s Ruby

Hooker Emerald Brooch

A 75.47-carat emerald set in a brooch, part of the Smithsonian Museum’s collection.

Black opal ring

422.99-carat Logan Sapphire from Sri Lanka. It is the heaviest mounted gem in the National Gem Collection, and is framed in a brooch setting surrounded by twenty round brilliant-cut diamonds, totalling 16 carats.

Star of Asia

329.7 carats star sapphire, and it’s part of the Smithsonian Museum’s collection.

Opal Peacock Brooch

This brooch is part of the Smithsonian Museum’s collection, and it was donated by Harry Winston Inc.

Maximillian Emerald Ring

Donated to the Smithsonian Museum by Marjorie Merriweather Post.