Clarity Enhancements: The Why and How

Why Clarity Enhance a Diamond?

Clarity-enhanced diamonds are interesting creatures in the diamond industry.  Some jewelers love to offer them as an affordable alternative to paying for a higher clarity grade, and others won't touch them with a 10-foot pole.  The most important point to remember about clarity enhancement is that it does not improve the clarity grade of the stone.  This might seem silly at first.  If the big black inclusions have been dissolved away or bleached out, why shouldn't the clarity grade go up?  The answer is that clarity enhancements are not natural and are not accepted as a normal part of the diamond finishing process.  They only improve the apparent clarity, or what the diamond looks like to the eye after the enhancements have been carried out.  A reputable gemological laboratory will grade the clarity of a clarity-enhanced diamond as if the inclusions were in their original state.  Ironically, these enhancements can actually worsen the clarity grade!  The purpose of clarity enhancement is to make the diamond more saleable to the consumer.  A jeweler can purchase a lower clarity diamond at a much more substantial discount than if purchasing higher clarity stones.  He or she then decides to have the diamond clarity enhanced with the ultimate aim or reaping a larger profit margin.

How Diamonds are Clarity-Enhanced

There are two main ways of enhancing the apparent clarity of a diamond: laser drilling and fracture filling.  These treatments may be appear separately or together in the same diamond.  Each method targets specific inclusions, and they are not a cure-all for included diamonds.

  • Laser Drilling - Diamonds are laser drilled in order to improve the appearance of dark, included crystals or staining caused by iron oxide.  An infared laser beam is aimed precisely at the inclusion, and it burns a microscopic hole (less than 0.2 mm wide) from the surface to the inclusion.  The heat of the laser can sometimes destroy the inclusion enough that no further treatment is necessary.  If not, the diamond is submerged in sulfuric acid dissolve the inclusion or to lighten the color of the inclusion.  Diamonds can actually have other diamonds in them as inclusions, and these cannot be removed because of diamond's immunity to sulfuric acid.  The laser leaves behind a permanent reminder of the treatment: a laser drill hole (LDH).  Laser drill holes become clarity characteristics that are taken into account when determining the clarity grade.  They are also noted on the diamond's plot.  The laser drill hole looks like a tiny tube extending into the diamond from the surface (not to be confused with a naturally-occurring growth tube).  To fill the hollow void left my the laster drilling, they might also be fracture-filled.  Laser drilling must be disclosed to the consumer.  GIA will grade laser-drilled diamonds so long as the laser drill holes have not been glass-filled.
  • Fracture Filling - Naturally-occurring breaks within a diamond can produce a white, feather-like inclusion that detracts from the beauty of the diamond.  To improve the look of these fractures, a special type of glass filling may be injected into the fractures.  The glass filling will ideally make the fractures more transparent and less noticeable.  If the fracture breaks the diamond's surface, the glass can be injected directly into it.  If the fracture is internal, a laser may be used to drill to fracture.  Laser drill holes themselves may be fracture-filled to diminish their appearance.  Fracture filling (and the accompanying laser drilling, if used) must be disclosed to the consumer.  Fracture filling is not considered a permanent treatment, as the glass come out of the diamond during normal wear, cleaning, or jewelry repairs.  Special care is required for fracture-filled diamonds.  Important: GIA will not grade fracture-filled diamonds.  This means that diamonds that are glass-filled to minimize the appearance of laser drill holes are ineligible for grading by GIA.  This is because it is not possible to accurately assess the pre-treatment clarity of the diamond.

Care and Disclosure

All diamond treatments must be disclosed to the consumer at every step of the sales process.  Diamond treatments such as fracture filling require special care and handling considerations.  These should be told to you by the jeweler.  The market for treated diamonds remains small compared to that of natural diamonds, so resaleability will be negatively affected.

Originally posted by me to on 4/6/2010.

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