Identifying and Pricing Clarity Enhanced Diamonds

Published March 2009

By Richard B. Drucker, GG
Publisher of The GemGuide

In a diversion away from colored gems, this article will delve into the clarity enhancement of diamonds. Even colored gem dealers are faced with diamond issues as they often mount the gems with accents of diamonds.

The clarity enhancement of diamonds is an inexpensive, easy to detect, method of improving the appearance of some lower graded diamonds. When a diamond has certain types of surface reaching “feathers,” they can be filled with a lead-glass substance to hide the feather. Many in the trade that do not like this treatment prefer to call it by its harsher sounding name of “fracture-filled.” Technically, these are not fractures so this is a misnomer, but the industry still uses this term.

While the feather may “disappear,” there will be a flash effect that is left in its place making the identification easy. To see the flash effect in a microscope, use the standard darkfield illumination and rock the stone back and forth. If a flash of color appears and changes when the stone is rocked to a new position, then it is proof of clarity enhancement. It is important to note that only one flash color is seen at a time, usually pink, green, or blue and then the color changes. If a feather is observed with a full rainbow of colors coming off the feather, all present at once, this is not a filled diamond. This is a naturally occurring strain pattern being observed. The key is that the full iridescent rainbow of colors will be seen at once if it is natural strain vs. a single color with a filled diamond. Also, with a filled diamond, there may be some tiny air bubbles present.

The treatment is stable under normal wear but can easily be damaged from the heat of a jeweler’s torch when repairs to jewelry are being done. When this happens, the filler can bead up at the surface. Internally, damaged filler often looks worse than the diamond did before it was treated. The filler can turn white or dry up leaving a cracked appearance, sometimes referred to as a “dried mud” look. A filled diamond should also be kept out of ultrasonic cleaners as the filler can be damaged with prolonged exposure. Boiling in acid will also destroy the filler. Since the filler may not be stable, the GIA grading laboratory will not grade a filled diamond. Other labs however, will grade these and add comments.

Pricing these diamonds can be difficult, mainly because there is no way of determining how much the clarity has actually improved. Typically, the improvement is one to two clarity grades but unless you see the before and after, you do not know. A grade of I1 for example, might improve to SI2 or possibly SI1. To evaluate the diamond, you can only state what it currently is (noting of course the enhancement), and then taking a discount for the filler. The normal discount experienced is in the 20%-40% range. This discount is off the price of the diamond as it is currently graded and if it were not filled. The discount should bring the price back down to somewhere between what the diamond might have been before treatment plus a small amount for the treatment itself. There is a cost to do the treatment and logic would say that the treatment is not done to lose money on the diamond but rather to make it more saleable and improve the appearance.

Whatever your personal feelings are toward this or any other treatment, the desire to buy, sell, or own one is a personal belief that varies with each supplier and each customer. The key is full disclosure of the process and proper pricing.

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