corundum, inclusions.5, gems

A 1.06-ct blue sapphire was submitted to the New York laboratory for identification. A spall cavity, the fire-skinned surface, and discoid fractures clearly indicated that the stone had been heat treated. However, the dark blue hexagonal color zoning seen through the table (figure 14) is unusual. It appears that a “phantom crystal” within the sapphire was affected by the heat treatment, leaving the edges fuzzy and partially diffused into the stone. When the stone was viewed with a Beck handheld spectroscope, the 450-nm (iron) line was quite strong. Perhaps this was originally a very dark sapphire that had been heated to lighten the color, with the perimeter of the “phantom crystal” remaining dark in spite of the treatment.