Showing results for recrystallization during cooling.

A 1.95 ct intense yellow (orangey) sapphire was recently submitted to our lab. The stone did not show any obvious heat-altered inclusions, besides blue color zoning related to bands of tiny particles (presumably rutile dust). However, the surface of the stone was more interesting and showed several areas where the stone’s surface had melted due to high temperature heating and subsequently re-crystallisation during cooling. On the pictures one can clearly see tiny gas bubbles in the re-crystallized areas. FTIR showed the characteristic features of a Be-diffusion treatment with bands at approximately 3053-1 cm, and 2490-1 cm.