Clarity Enhancement of Diamonds – Part 1 – Laser Drilling

 

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Hi Again,
I am going to discuss the important subject of Clarity Enhancement of Diamonds. It is a long but important discussion and well worth your time to educate yourself on this issue.

The clarity, or purity, of a diamond — the relative or apparent severity of flaws within the stone — has, like the other “four Cs”, a strong bearing on the evaluation of a diamond’s worth. The most common flaws, or inclusions, seen in diamonds are fractures (commonly called feathers, due to their feathery whitish appearance), and solid foreign crystals within the diamond; such as garnet, diopside, carbon or even other diamonds. The size, color, and position of inclusions can reduce the value of a diamond, especially when other gemological characteristics are good. Those who prepare diamonds for sale sometimes choose to reduce the visual impact of inclusions through oe or more of a variety of treatments.

This discussion will focus on the two major forms of “enhancements:” Laser Drilling and Fracture Filling. There is a big difference between these two methods of improving the look of a diamond as will be described. In this post I will discuss Laser Drilling of Diamonds. In my next post, I will discuss Fracture Filling of Diamonds.

Laser Drilling of Diamonds

The development of laser drilling techniques on a microscopic scale, has enabled diamond manufacturers and cutters to selectively target and either remove or significantly reduce the visibility of crystal or iron oxide-stained fracture inclusions. Diamonds have been laser-drilled since at least the mid-1980s. Most often it is used to whiten a black carbon crystal which is prominently visible in the diamond to the naked eye. Since the development of the laser drilling technique, and until more recently, laser drilling was an accepted part of the diamond manufacturing process. It is still used today on diamonds which have a significant presence of black carbon crystals imbedded in the diamond.

The drilling process involves the use of an infrared laser to bore very fine holes, or tubes, into a diamond to create a route of access to an inclusion. Once the included crystal has been reached by the drill, the diamond is immersed in sulfuric acid and the acid travels down the tube to dissolve the carbon crystal or iron oxide staining.

Several inclusions can be thus removed from the same diamond, and under microscopic inspection the fine bore holes are readily detectable, usually when the diamond is viewed from the side or bottom of the diamond.

Unlike fracture-filling (to be described in my next post), a laser drill hole is considered by the Gemological Institute of America’s Diamond Trade Laboratory to be an internal inclusion which is marked on their certificates just like other inclusions such as feathers, clouds and crystals. This is because the process of laser-drilling is a permanent process. In contrast to fracture-filled diamonds, the GIA does issue their certificates (called “Diamond Grading Reports”) for diamonds which have laser drill holes in them. The following is a direct quotation from GIA’s website concerning the range of diamonds for which the GIA Laboratory will and will not issue certificates.  

“GIA Diamond Grading Reports are not issued for synthetics, simulants, mounted diamonds or those that have undergone unstable treatments, such as fracture filling or coating. And while reports may be issued for diamonds that have been laser drilled or HPHT* processed, these stable treatments are prominently disclosed on the report.” [Emphasis added] *HPHT is a synthetic process designed to artificially improve the color of a diamond.

A diamond which is certified but which has a laser drill hole as one of its inclusions is not as valuable as another diamond of the same grade which does not have a laser drill hole. At A. Fishman & Son, we do not sell diamonds with laser drill holes.

My next post will cover Fracture Filling enhancements, a much more controversial method of enhancement, and what you, a diamond purchaser, should do when you go to buy a diamond.

So, in the meantime, until next time, Mind Your Diamonds!

Josh Fishman

www.afishman.com

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