Growth or Treatment: Polymer coating to color enhance
Identification Tools Required: Magnification.
How to Identify:
Primary Test: This is a fairly new version of an old treatment. Polymer impregnation of gemstones has been around for decades in jade, opal, etc... In this case the polymer coating adds both color and durability to the stone. In the image below it is easy to see the polymer coating on the stone at 30x. By comparing to the 30x image of natural, untreated Lapis Lazuli it is easy to identify.
Secondary Tests: We tried a number of substances to cut through this polymer coating and could not. Acetone bath did not affect the stone. No secondary tests should be required, however, as the coating is easy to see under basic levels of magnification.
Repair and Setting: Extreme care should be used when handling these stones for repair or setting. The true durability of this treatment is not known at this time. As listed above the material does not break down with acetone, although long term acetone bath may affect the coating. Heat and pickling solution may affect the coating and significantly alter the appearance of the stone.