Micro-World Gems & Gemology, Winter 2018, Vol. 54, No. 4

Drill Hole in Heated Pink Sapphire


Drill hole in heated pink sapphire
Figure 1. A drill hole in a heated pink sapphire from Myanmar, seen with diffuse brightfield and fiber-optic illumination. Photomicrograph by E. Billie Hughes; approximate field of view 5 mm.

While testing a faceted pink sapphire in our laboratory, we looked at its internal features and determined that it was a heat-treated stone from Myanmar. As we examined the surface of the 14.75 × 13.02 × 8.82 mm sapphire, we noticed an unusual feature: a large round drill hole extending from the surface into a crystal or negative crystal within the stone (see above). Note that this drill hole did not extend through the sapphire, as one might see in a bead. This stone was faceted, so it is unlikely that the person who drilled into the stone intended to create a bead.

What seems more likely, given the placement of the drill hole, is that it was drilled to minimize the appearance of the crystal that it reached. We suspect that the crystal was originally more opaque and of darker color or filled with a dark substance. It is possible that the drill hole was created so that the crystal could be cleaned out with acid, minimizing its appearance. We can only guess at the intentions of the treater, who might have gotten the idea from the laser drilling of diamonds.

Although the exact process may remain a mystery, this inclusion indicates an unusual treatment in ruby and sapphire.

E. Billie Hughes is a gemologist at Lotus Gemology in Bangkok.