Treatment of Emerald, Aquamarine and Morganite Beryls

Beryl is a large and important family of gemstones which includes both aquamarine and emerald.  When free of color causing impurities or any radiation induced coloration beryl is actually colorless. The presence of the elements chromium and vanadium give the green coloration of emerald, iron gives both yellow and the blue of aquamarine, whereas morganite and the Utah red beryl are colored by the presence of manganese.

A large percentage of the aquamarine which is used in jewelry comes out from the ground in a greenish blue shade.  At one time, this more greenish shade was the preferred color for aquamarine gems, however the winds of fashion have shifted in recent decades and blue is now the preferred color.  In order to remove the yellowish under him tone that makes the aquamarine appear green, gentle heating is needed.  Temperatures between 250 and 400°C are best.  Only a few hours time is needed to effect the change.  Care must be taken to heat the stones slowly as the stones do have some sensitivity, and it is possible to create heat induced fractures. Where desired, additional yellow coloration in beryl gems can be induced through irradiation.  This is basically the reverse of the process of heat treatment noted above which removes the same yellow coloration.

Some morganite which tends towards orange or salmon colors can be changed through the same heat treatment noted above to remove the yellow element, leaving a pure pink.  The temperatures and necessary precautions are the same as noted for aquamarine.

Emerald is not normally treated by heat or radiation, but there are numerous treatments to improve the appearance of emerald gems.  Perhaps the biggest problem with emerald is its tendency to be cracked and flawed. Clean, transparent and well colored emeralds are both rare and valuable.   For centuries men have treated emerald gems with oils, waxes or plastics to fill in the open spaces and cracks, making the gem appear more transparent and attractive. A thorough cleaning followed by immersion in the fluids under a strong vacuum is a technique used to draw the fluids into the stone.  At times, these substances have also been dyed green in order to enhance the green coloration of the emerald.  A large percentage of all emeralds in commercial jewelry have been treated by some version of this technique. Unfortunately, the materials which are used to fill the voids are not nearly as strong or stable as the emerald itself.  Stones which were weak through the presence of cracks and other flaws do not become appreciably stronger through the process of filling them, and any structural weakness that was originally present still remains.  As a result, these stones are far more subject than one would expect to damage the impact or other blows while being worn, especially when used for rings. This type of filling treatment should always be disclosed to the buyer.

A new or more high-tech method has been used in recent years for the enhancement of emerald gems.  Techniques have been developed to actually grow over coatings of a synthetic, man made deep green emerald onto pale emerald and other beryl gems.  The coatings are generally thin and often can be easily noted when specific types of testing equipment are used.