Fracture-Filled (Clarity Enhanced)
The term clarity enhanced is a more polite term for fractured-filled diamonds. All the same, fracture-filled diamonds are now a mainstream treatment for clarity improvement. A silica-type substance (similar to glass) is heated to a liquid state and forced under pressure into the open inclusion. When using the term "open", this can refer to a hairline opening at the stone's surface. Laser drill holes are also used to insert the filling when the fractures are not accessible from the surface.
All the companies treating and selling fractured-filled diamonds, guarantee the treatment for life, and are willing to re-fill a diamond that has been adversely affected. With age, or depending on the amount of light exposure, the filling will darken or discolor over time. Again, the companies selling the product have made it clear that the treatment will be re-administered for no charge.
At this writing, fillings are becoming more difficult to detect. A flash effect due to the filling, is usually present and is unmistakable: Shades of blue, violet, green, and other colors give it away. Often the flash effect is very subtle and can be easily overlooked. This is another very good reason to meticulously scrutinize every diamond that comes your way to make sure that it does not cause serious problems in resale or to the buyer's regret.
It is of utmost importance to represent fracture filled diamonds as such, both from an ethical point of view and from a "diamond trade rules" point of view. These diamonds are discounted considerably depending on the outcome of the treatment.