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!