Diamond Treatments

For as long as diamonds have been used for adornment, man has developed creative treatments to alter or improve color or clarity. Disclosure of any or all of these treatments by the seller is required by the Federal Trade Commission (FTC).

Fracture Filling

Fracture filling is a treatment in which molten high refractive index glass filler is drawn into surface-reaching feathers to enhance the apparent clarity of the diamond. The improvement in appearance can be dramatic.

Repeated ultrasonic and steam cleaning and the heat from a jeweler’s torch can damage the filler, causing it to degrade and making it appear cloudy over time. It is important if you own a diamond that has been fracture filled to inform a jeweler prior to having work performed on the piece.

Laser Drilling

Laser drilling was first used as a means to improve the apparent clarity of a diamond during the 1970’s. A concentrated beam of laser light is directed at a diamond’s dark inclusions which are subsequently bleached with acid to make the inclusion appear lighter. Because laser drilling is permanent, gem labs report them as clarity characteristics.

While laser drilling does not improve a clarity grade, it makes the diamond easier to sell by making a dark inclusion appear lighter. Early drill holes were large and more obvious; improvements in technology have resulted in smaller drill holes being produced. A new lasering technique, called internal laser drilling, produces tiny cleavages that form a step-like progression to the surface of the diamond, still allowing the inclusion to be bleached while resulting in a more natural appearance than the traditional drill holes. It is not uncommon for the bleached inclusion and drill hole to be masked by fracture filling.

High Pressure/ High Temperature (HPHT)

HPHT is a diamond color modification process that uses equipment and conditions similar to those used to grow synthetic diamonds. Some types of diamonds exhibit a brown color caused by distortions of the diamond’s crystal structure. High pressures and temperatures can eliminate the brown color by reducing or removing these structural distortions.

Fancy colors, such as pink, greenish to orangy yellow or blue, can also be produced by HPHT. This process is one of the most challenging for gem labs to identify. The technology needed for identification of HPHT is out of the range of most stores and independent gemologists.

Irradiation

Irradiation of diamond is commonly performed to alter color, producing yellows, deep blues and greens. Exposure to natural radiation may also produce a green color – often the source, whether natural or induced by man, is not determinable. Irradiated diamonds may subsequently be annealed, or heated, to remove characteristics that allow all but the major gem labs to positively identify the treatment.

Surface Coatings

Rarely done today, the coloration of diamonds by artificial coatings was one of the developments that caused the FTC to revise its guidelines in the late 1950’s to address treatments of diamonds.

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