Imitation: Dyed Sillimanite
Identification Tools Required: Magnification and refractometer.
How to Identify:
Primary Test: Magnification should be diagnostic for this material as the fibrous structure is unlike anything natural for emerald. Also, under even at low power magnification the color dye can be seen within the fiber structure as demonstrated in the images below.
Secondary Tests: The refractometer is a diagnostic test to confirm the status of this material. And a refractive index range of 1.653 - 1.685 it is both far above that of beryl, and the birefringence is so great that there should be no confusion of this material with natural emerald.
Repair and Setting: Most of this material is quite porous and can be heavily fractured. Care should be taken regarding any cleaning as an ultrasonic will most likely remove the dyes used to color the stone. Care in prong setting should also be used as the highly fractured and fibrous nature of this stone will make it subject to breakage during the prong setting process. Cannot be subjected to heat even when used with a heat sink.