Recently, the Diamond Dealers Club had an interesting briefing by Nicholas Del Re, GG, B.Sc., manager of gemological services for the European Gemological Laboratory USA on the KM laser treatment.
Del Re said that in the past decade, lasering technology has become increasingly sophisticated. Israeli drillers developed a new kind of drilling, called Kiduah Meyuhad, meaning “special drill” in Hebrew. Instead of a traditional laser drill hole, the KM produces a sheet-like feather running up to the surface, which is visible via normal ten power magnification. It can be very natural looking and if the treatment has successfully bleached out the black inclusion, it can be difficult to distinguish the KM treated inclusions from natural ones.
In the past year, EGL has seen a new generation of the treatment — “Micro KM.” At 10-power and even 100-power magnification, the laser drilling appeared to be confined with the diamond, so it looked like it had not been treated. The only way you can see this new treatment is under 200– and 1,000-power magnification.
To demonstrate how small this treatment is, Del Re noted that the break in the surface is approximately five microns. The width of a human hair is only 80 microns. In other words, this treatment makes the drill hole basically invisible.
We think this new treatment raises a serious issue, even though it is only available for SI grades or below. After considerable debate, the Federal Trade Commission rules a few years ago that you must disclose laser drilling. This is now the law. But unless the stone is certified, how could any jeweler disclose something to their consumer that can’t even be seen under a 100-power microscope? And even if they did tell them, does knowledge of such a minute hole help the consumer in any way?