Page "Emerald" Paragraph 17

Hydrothermal synthetic emeralds have been attributed to IG Farben, Nacken, Tairus, and others, but the first satisfactory commercial product was that of Johann Lechleitner of Innsbruck, Austria, which appeared on the market in the 1960s.

These stones were initially sold under the names " Emerita " and " Symeralds ", and they were grown as a thin layer of emerald on top of natural colorless beryl stones.

Although not much is known about the original process, it is assumed that Leichleitner emeralds were grown in acid conditions.

Later, from 1965 to 1970, the Linde Division of Union Carbide produced completely synthetic emeralds by hydrothermal synthesis.

According to their patents, acidic conditions are essential to prevent the chromium ( which is used as the colorant ) from precipitating.

Also, it is important that the silicon-containing nutrient be kept away from the other ingredients to prevent nucleation and confine growth to the seed crystals.

Growth occurs by a diffusion-reaction process, assisted by convection.

The largest producer of hydrothermal emeralds today is Tairus in Russia.

They have succeeded in synthesizing emeralds that have similar chemical composition as emeralds in alkaline deposits in Colombia, hence they are called “ Colombian Created Emeralds ” or “ Tairus Created Emeralds ”.

Luminescence in ultraviolet light is considered a supplementary test when making a natural vs. synthetic determination, as many, but not all, natural emeralds are inert to ultraviolet light.

Many synthetics are also UV inert.