The author recently examined a 2.56 ct purple octagonal step-cut sapphire. This sapphire contained a negative crystal with a sharp rectilinear zigzag-patterned fingerprint, providing strong evidence that no heat treatment took place. Under fiber-optic illumination, the fingerprint displayed vibrant colors due to thin-film interference. The combination of the fingerprint and negative crystal created an image reminiscent of a digital butterfly (see above). Both the negative crystal and the unique fingerprint were caused by the natural healing of a surface-reaching fracture in the sapphire host. The healed areas parallel to the c-axis displayed rectangular outlines, resulting in the “cyber” appearance of the wings.
The author recently examined a 2.56 ct purple octagonal step-cut sapphire. This sapphire contained a negative crystal with a sharp rectilinear zigzag-patterned fingerprint, providing strong evidence that no heat treatment took place. Under fiber-optic illumination, the fingerprint displayed vibrant colors due to thin-film interference. The combination of the fingerprint and negative crystal created an image reminiscent of a digital butterfly (see above). Both the negative crystal and the unique fingerprint were caused by the natural healing of a surface-reaching fracture in the sapphire host. The healed areas parallel to the c-axis displayed rectangular outlines, resulting in the “cyber” appearance of the wings.
