Laser Drill Holes

We tend to imagine lasers as something dramatic, but in diamonds, a laser drill hole is much smaller than it sounds. In fact, most are invisible to the naked eye and only show up under magnification.

The process behind it is fairly straightforward. A microscopic tunnel is created using a focused laser beam. The purpose? To reach and remove a dark or unsightly inclusion, usually a black crystal. Once the tunnel is made, a strong acid is introduced to bleach or dissolve the inclusion, improving the visual clarity of the diamond.

In a GIA clarity plot, laser drill holes are marked as a tiny red dot with a green outline. However, if the surface entry point is no longer visible perhaps due to being repolished, you will usually find a comment in the grading report that says “Internal laser drilling is present.”

Laser drill holes are relatively rare. Most diamonds are not treated in this way, especially those with clarity grades of SI1 or higher. You’re unlikely to encounter them unless you’re specifically browsing lower clarity stones or treated diamonds.