by Allan Taylor

Created on: September 19, 2011   Last Updated: September 24, 2011

Emeralds have been prized by man and worn as adornment by women for several thousand years. Cleopatra loved emeralds which conveniently were mined close to home from the Red Sea deposits.  This lively green gemstone was fashioned into beads and cabochons and eventually faceted gems. Emerald was imitated by other green stones and manmade glass, or pastes.

The precious gemstones diamond, ruby, sapphire and emerald have always been admired by man and attempts made to synthesize them in the past  The synthetic gemstone industry began in the 1900’s with the invention of the flame fusion process to grow ruby and sapphire ( colored corundum) by  crystallization  from the melt.  Today world production amounts to hundreds of  tonnes per year.  Attempts to grow emeralds by this method failed due to the melt forming a glass on cooling,  emerald being a silicate mineral having 67% silica.

It is necessary to give emerald a helping hand to nucleate and grow and this is done by using a flux or mineralizer to mobilize the silica in the system.  The first successful commercial production of a flux emerald, having the trade name “Igmerald”, was in the late 1930’s by the German chemical company I. G. Farbenindustrie, but was discontinued during WW2.  A lithium polymolybdate flux was contained in a large platinum crucible and an isothermal diffusion process used to combine the components beryllia, alumina and silica  to form emerald at 800 degrees C (1).     In the USA a similar flux process was developed by Carroll Chatham in San Francisco with appreciable emerald production in the 1950’s (1).  Today the business continues as Chatham Created Gemstones producing also synthetic rubies, sapphires and alexandrites.

Another way of growing emeralds is by the hydrothermal process which after the last war was perfected to grow quartz crystals for electronic uses. We all carry “quartz” watches today. It was not just a simple matter of substituting beryl for quartz in the process, but took a decade or more to develop the method for emeralds, and research is ongoing.

The first fully synthetic hydrothermal emeralds were produced by the Linde Company, Division of Union Carbide, at Buffalo, NY in the 1960’s.  Steel pressure vessels were used to contain water and a mineralizer at ca 600 degrees C and up to 1000 bars water pressure.  Seed plates of clear

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