Synthetic sapphires

by Ardamun Ramdeva

Having identical chemical composition and physical properties of natural sapphires, synthetic sapphires, over the years, have achieved a high degree of perfection. The many different methods of producing synthetic sapphires are: melt growth, solution growth, or extremely high-temperature, high-pressure growth processes.

Synthetic Sapphires – Gemstones Par Excellence

Sapphire was first synthesized in 1902. Synthetic Ruby – the ‘red sapphire’, though, was produced in 1888 by the French chemist, Auguste Victor Louis Verneuil, through flame fusion process. A synthetic sapphire or the one created in a lab, under controlled conditions, has crystal structure, optical properties and chemical composition of its natural avatar. Some synthetic processes simulate the geological conditions required to produce natural sapphire. Both, Sapphire and Ruby, are varieties of corundum, a crystalline form of aluminum oxide. In nature, corundum comes in various shades of blue, as well as colorless, red, yellow, pink, orange, brown, purple, and green. Corundum of all colors is known as Sapphire, except the red sapphire, which is known as Ruby.

The word sapphire is known to originate from the Latin ‘sapphärus’, Middle English ‘saphir’, Old French ‘safir’, Greek ‘sappheiros’, and Hebrew ‘sappîr’.

Production of Synthetic Sapphires

Synthetic sapphires come in almost all colors, but the most sought after is the deep blue sapphire. Basically, to get different colors, dopants are added to aluminum oxide. Sapphires are synthesized by melting these at over 2000º Celsius. Having identical chemical composition and physical properties of natural sapphires, synthetic sapphires, over the years, have achieved a high degree of perfection. The many different methods of producing synthetic sapphires are: melt growth, solution growth, or extremely high-temperature, high-pressure growth processes.

The flame fusion process of Auguste Verneuil involves producing a boule from finely ground form of aluminum oxide, or Alumna, with the help of an inverted oxyhydrogen torch. Boule is a mass of alumna with the same physical and chemical properties of corundum. Oxygen passes through a chamber containing highly purified alumna, and this is carried to the central part of the oxyhydrogen flame. The fine alumna particles fuse and fall down as molten boule. Flame, rate of the feed of alumna, and the lowering of boule are controlled and adjusted to produce a boule of uniform size and shape. To produce colorless sapphire, the melting point of boule is 2030º Celsius. The furnace is shut down once the boule reaches the desired size of 150 or 200 carats, and is allowed to cool.

The Kyropoulos method of producing synthetic sapphires involves growing sapphire crystals under controlled conditions. During the process of crystallization, sapphire crystals sprout in cylindrical shapes. The required diameter of the crystal is maintained by the automatic displacement of the seed crystal, without rotation. The melt is achieved through resistive heating. The Kyropoulos method produces sapphire with minimal mechanical stress.

The Czochralski (pulling) process involves melting the powdered ingredients in a platinum, iridium, graphite, or ceramic crucible. A rotating rod, with a seed crystal attached to one end, is lowered to touch the melt. The rod is slowly withdrawn at the rate of 1 to 100 millimeters (mm) per hour. As the seed pulls the material from the melt, it cools and solidifies. Very high purity large crystals of more than 50 mm in diameter and 1 meter in length are grown by this method.

Some of the other processes for producing synthetic sapphires are: the floating zone process, the flux process, and the hydrothermal process.

Uses of Synthetic Sapphires

There are many uses of synthetic sapphires – as gemstone, as well as non-gemstone. Sharing the physical, chemical and optical qualities and properties of the natural sapphire, the synthetic sapphires are used extensively in jewelry. Some of the synthetic sapphires are so perfect that it becomes difficult to identify them, unless by an experienced jeweler or a gemologist. Padparadscha sapphires are rare orange-pink variety of sapphires and have a higher value than even the blue sapphires. These sapphires have been created in labs. They are so perfect that a few years ago, the synthetic Padparadscha sapphires were rated as natural till the American Gem Trade Association (AGTA) found out they were not so.

Jewelry produced by synthetic sapphires is just as beautiful as the one by natural sapphires. Though not inexpensive, synthetic sapphire jewelry costs less than that of natural sapphire. Synthetic sapphires range in price and size, and the smaller sapphires are used in less expensive jewelry. As a matter of ethics, the origin of the sapphire should always be disclosed. Though synthetic sapphires can technically be called ‘genuine’, they are certainly not natural. One should learn about synthetic sapphires before buying jewelry, to know what one is buying.

Other applications of synthetic sapphires include their use in watch and semi-conductor industries. It was first used as watch crystals in the 1960s. It is used in most high-end watch brands. Synthetic sapphire crystals are grown in cylindrical ingots. These ingots of pure synthetic sapphires are sliced into wafers. These are polished into transparent crystal slices. High quality watches use these slices as watch faces. The exceptional hardness of the material makes the watch face impossible to scratch.

Wafers of single crystal synthetic sapphires are used in semi-conductor industry for light emitting diodes. For its extreme abrasive resistance, synthetic sapphire is the jewel of choice. Its other features include, zero porosity, extreme hardness, low-friction coefficient, chemical inertness – even to hydrofluoric acid, high thermal conductivity, and excellent wear resistance. Due to zero porosity, micro-finishes of two can be attained.

Precision jeweled bearing rollers use sapphire balls for their low-friction and long-wear applications. Some advantages of using synthetic sapphires as jeweled bearings are:

* Low friction, hardness and shock resistance
* Close tolerances
* Accurate wear life
* Non magnetic properties
* Resistance to heat, corrosion, and distortion

Due to their high melting point of 2000º Celsius, they are suitable for high-heat applications also. The other uses of synthetic sapphires include electronics, optoelectronics, optics, and laser technologies.

Identification of Synthetic Sapphires

* Presence of round, elliptical or flask shaped bubbles.
* Whitish sheen seen in natural sapphires is missing in synthetics
* Strain cracks, curved striae (fine thread-line lines or streaks), wispy white veils, etc
* Flux inclusions and non-natural gas inclusions
* Visible seed crystals in synthetic sapphires
* Color zones seen when dipped in Methylene Iodide.
* Absorption spectra not seen in synthetic sapphires.
* Unnatural looking colors.
* Dark un-fused blotches seen. Caused by coloring matter.
* Variation in properties of fluorescence.
* Transparency to Ultra Violet light varies.
* Star effect in synthetic sapphires seems to be painted.
* The synthetics have a neatly ground out base as against the lumpy base of natural sapphires.

How to differentiate synthetic and natural sapphire

by Ashutosh Roy

A deep look shows signs of slow crystallization in case of natural sapphires. Sometimes some external elements in very small quantities are visible in original sapphire like most other gemstones.

Sapphire – Natural versus Artificial

Natural gemstones are taken out directly from the marvelous treasures of the mother earth. Then they are only washed, polished and cut into proper shapes. They are directly sold in the market keeping their originality intact without any intervention by human beings. They are never “processed” or “treated”.

Likewise Synthetic gemstones are gifts of technology marvels and the very process indicates how to create a new form using all natural elements and solutions. The challenge in Synthetic gemstone is how closest it can hold the look and feel of the natural one.

As the time changes real things are getting imitated as a rule of the human nature. May be, its for comfort, fashion or money-making urge of the greedy scientists engaged in the process. We all are habituated in the artificial cooling by air-conditioner. We may see, how an artificial shower pours down in a film. A test tube baby is also generated from a sterilized mother to see a laughing face, who would not otherwise have a natural baby for her thirsty heart. Similar is the case with a gemstone. Remember a synthetic gemstone has got the exact replication of the natural one in terms of physical and chemical properties. The look and feel and the optical qualities also remain the same. In short, glimpse and glitter remain the same.

Now if we consider the case of Sapphire, it’s a birthstone of September; physically it belongs to the variety of mineral corundum. Now for the natural science students, all varieties of corundum excepting the red one are called Sapphire. The word comes from the Greek Sappherious. Astrologically, Sapphire seems to have magical power even for alleviating long-term misfortune and in particular, to cleanse the jumbled up thoughts to generate a wider vision, clarity and self-confidence. It was perhaps invented in the 19th century for crystal watch and today it’s a common phenomenon to use sapphire (natural or artificial) in high value watches because of its glittering appearances.

Now lets have a closer look into the synthetic sapphire. It’s definitely very hard like the natural one, which is approximately 9 in Mohs Scale. Synthetic sapphire is made from the crystallization process of aluminum oxide at a very high temperature. The Verneuil technique is used for making synthetic sapphires. Researchers have tried by varying concentrations of Ni2+, Ni3+ and Cr3+ to generate a wide spectrum of colour.

It’s very difficult to distinguish between the synthetic sapphire and the natural one. A deep look shows signs of slow crystallization in case of natural sapphires. Sometimes some external elements in very small quantities are visible in original sapphire like most other gemstones. The inclusions may be finger prints or like feathers or even may be like laces. If you don’t find any of them, try through magnification. Reddish tints, polysynthetic twinnings are very common to natural sapphires. The hexagonal patterned angular lines are found in Sapphire. “Negative Crystals”, the cavities, are found in natural Sapphires. Impurities of any sort are the most common phenomena in case of Natural Sapphire.

If you compare the natural sapphire with that of Synthetic one, you will notice bubble like inclusions. Even feather like inclusions are also possible in case of natural ones. If they are placed under strong light, the shining becomes abnormal. But again its very difficult for the normal eyes to detect. Inclusions of various types can be tested by fiber-optic lighting. In case of synthetic one, the coloring agents give the gemstone its various artificial hues, which are never present in case of natural one. But remember the synthetic sapphire is not that disparaging like most other synthetic gemstones; sometimes even people ask for synthetic sapphires for their jewelries and watches.

Remember the watch glass producers always prefer colorless synthetic sapphire. The Surface diffusion-treated corundum (SDTC), the revolutionary concept, has been accepted widely, for its coating functionality. Even being a processed sapphire, the SDTC has gained enormous popularity. “Cathodoluminescence Analyses” by Prof. K. Ramseyer at the University of Berne, Institute of Geological Sciences, Berne (Switzerland) have contributed to the design of fancy sapphires, which have again been accepted widely though being these fancy sapphires belong to the category of processed sapphire.

Experts suggest, rub a gemstone in your palm and squeeze it between your fingers. The synthetic one will give you a waxy feel. Testing laboratories use different methodologies to identify the synthetics ones. Experienced eyes of gemologists can detect the synthetic one even by naked eyes and by its touch and feel.

The ultraviolet radiation process is highly helpful for identification of Synthetic Sapphire. Sometimes the specific gravity comparison can also help to identify the natural one. The refractive index test is also useful for distinguishing between the natural and the synthetic one. The synthetic sapphire glows abnormally in the Special lighting effect. But again as an exception, even the natural orange sapphire is highly fluorescent. So don’t get confused! The microscopic view of synthetic sapphire shows the “Curved Striae”, which are colored curved bands in the sapphire. UV Fluorescence is used in many laboratories as a Gemological tool to identify the synthetic stones. Some uses the highly complicated testing method like Secondary Ion Mass Spectrometry (SIMS) for testing the natural sapphires. But the caution message is that heating is never a normal procedure to test a sapphire. Richard W. Hughes in “CORUNDUM IDENTIFICATION IN A NUTSHELL”, advises “complete Fe Spectrum of lines at 451.5, 460 & 470 nm. is proof of natural origin”. Perhaps this is the best full-proof solution.

If you are a novice, try to go to a genuine gemstone mart, which is recognized or of immense repute. You may also try your personally known jewelers. Its always preferable to take help of reputed Testing & Research Laboratories like Gem and Jewelry Institute of Thailand (GIT), American Gem Trade Association (AGTA), Gemological Institute of America’s Gem Trade Lab. There are several grievance redressal forums today like “Jewelers Vigilance Committee” (Website: http://www.jvclegal.org) to address and take action on your complains.

So if you really do believe in the myth that sapphire contaminated water even can save you from scorpion bite, try to be sanguine about the originality of the gemstone, else you may even risk your life!

Sapphire facts

by Seema Susheel

The change in color is due to different element present inside the core of the sapphire crystal. For example if there is an element like Titanium then the crystal reflects blue and hence is blue in color. There is no limit to the saturation of colors in a sapphire.

Sapphire facts and buying guide

Sapphire is the royal semi-precious stone which is been used in jewelry from ancient times. There are known facts that many royals have used sapphire on there crowns, brooches, wedding ring etc. The special quality of this beautiful gemstone is that it’s the hardest stone naturally found. The hardness of this semi-precious stone is just second to that of the diamond. The sapphire being hard in nature sapphire jewelry is durable and recommended to be passed upon as an heirloom.

Sapphire – Origin
Sapphire deposits are found in large quantities in Sri Lanka. Sapphire is been found in Sri Lanka from ancient times and even now it’s a popular destination for good quality sapphires. There is a typical orange pinkish sapphire found only in Sri Lanka and it resembles a lotus. Sri Lanka is the largest producer of this beautiful gemstone. Sapphire is also found in countries like Madagascar, Burma, India- Kashmir, America, Thailand and Cambodia.

Sapphire – Type and color
Sapphires are members of the corundum family of minerals. They come in all types of colors from blue to black and all colors in between. The change in color is due to different element present inside the core of the sapphire crystal. For example if there is an element like Titanium then the crystal reflects blue and hence is blue in color. There is no limit to the saturation of colors in a sapphire. The saturation of the color depends on the amount of mineral present inside the crystal. Many times there are combination of minerals which result in different hues and saturation of the same color. Sapphire comes in colors like blue, pink, yellow, colorless, black, white, orange, and brown. Among sapphires no two sapphires look alike. Most sapphires are treated and given heat treatments to make them commercially valuable and improve there clarity and shine. The blue sapphire itself comes in varied colors of blue like the baby blue to deep sea blue, with a mix of green and yellow they form wonderful color combinations. Blue sapphires are the most popular because of its amazing color which has mesmerized even the royals. Even today the blue sapphire is the most sought after colored stone. The pink sapphire is a favorite among jewelry designers who use this stone in combination with diamonds and white gold for amazing creations.

Sapphire – Buying Information
Sapphire is very rarely found, it is much rarer then the diamond, hence the market price for this stone is on a rise. It’s safe and sound to invest in a fine quality untreated sapphire then in any other jewel as there sure to be value add to this stone. The demand is more and the production is not so much to match the demand. A natural uncut, untreated sapphire with fine quality of color and shine is jewels an ardent jewelry lover will surly keep in his collection. There are treated sapphires also available. There is a difference in price among sapphires depending on the color quality, whether its treated or untreated, carat size, shine and brilliance. Though the most popular color is blue and pink the choice of color is a personal choice and with sapphire you can find them in many colors.

Sapphire- Buying shops
As popular and available the diamond is, the sapphire though popular is not very easily available. You can find hundreds of jewelry shops and websites selling diamonds. The same is not with sapphires simply because it’s much rarer then diamond. Few authentic serious gems traders who have set up there shops on the internet is the shopping stop for the ones who want the royal indulgence to be there own. These websites will give you extensive information on the sapphire and also provide you with wide range in prices, sizes and colors. If the sapphire is extremely outstanding with flawless color and shine then its something you can make your own. The price differentiates depending on the quality and the carat size. Once you have decided on the type of sapphire then you can buy it to use in jewelry like finger ring, a pendant or a brooch. You can even go for boutique fashion jewelry sites where in you could select one of the readymade jewelry pieces where blue sapphire or pink sapphire is tastefully used with other metals and stones to create amazing neck pieces and matching ear rings. Bracelets, waist bands, accessories – sapphire has found its use in many items. The price for sapphire jewelry could be similar to the expensive diamond set you were eyeing but the difference is you are paying for the beauty and quality which is rare and one of its kind.

Sapphire Buying – feel the beauty before you make it your own.
There are many gems traders who deal with buying and selling gemstones. These jewelry shops are in this business from generations. Many jewelers are in this business for so long that for then to gauge a quality sapphire is as easy and simple as drinking water. You got to be lucky to find such a shop by yourself but with little effort you surely can come across one where in you can buy the royal blue sapphire and trust the jeweler to give value for you money. You are wishing to buy sapphire to wear it as a locket or for any other use when you are buying just the single stone then you have to look at the clarity of color, size that suits your design and consequently the price. The jewelry shops are the places where the jeweler will take you through viewing different kinds of sapphires colors and sizes. You can see and feel the beauty of the sapphire you buy before making the purchase. This kind of luxury is only for those who can afford to take time off there busy schedules and put in the time and effort to go shop hopping to look for the right sapphire that will win there heart. Once you have found something that you love then it’s easier to shell out money. A purchase like sapphire won’t make you repent in future as its valuable forever.