The practice of gem simulation has a long colorful history. In fact their are records of ancient Egyptian craftsmen faking Lapis Lazuli, Malachite and Turquoise. The materials used to create simulants include plastic, Porcelain, Hematite,and Glass.
Composite Stones:
Basically what these are is when a thin slice of stone is attached to a piece of faceted glass.
Synthetics
During the the 19 th century in Germany and France experiments where conducted to synthesize precious stones. These focused on the flax- melt process either using small fragments of the actual gems or salts that contained the basic elements of their composition.
Flame Fusion Process
French Chemist August Verneuil came up with the flame fusion method that is still in use today. Powdered ingredients are dropped into a furnace and melt as the fall through a flame hotter than C fusing into liquid drops. Dripping onto a pedestal they crystallize and form a long cylindrical crystal which is known as a boule
Gilson Gems
Unfortunately in the modern world of today where profit is everything synthetics abound. The French manufacturer Gilson produce Laps Lazuli, Turquoise and coral. Although technically not true synthetics due to the difference in their physical and optical properties.
These products are very commonly found in cheap Indian Jewelery on Flea Markets.
Imitations
Glass has for centuries and still is used to imitate gemstones.Glass is usually warmer to the touch and to a trained hand quite easy to distinguish
Opal Imitations are favorite and again Gilson the French manufacturer was very successful.
Enhancements
Enhancements through Heat Treatment, Irradiation, Oiling and Staining are often more difficult to detect.Fracture filling and Color Diffusion is popular with stones such as Sapphire and Ruby. The problem being that a buyer is under the impression they are buying a fine stone only to find out years later that it is almost worthless
Valley Gems provides a Gem Identification, Certification and Valuation Service. Our section under products has more information
