Diamond Treatments By an Expert Gemologist Jinagna Shah

Diamonds are natural stones which form inside the earth's mantle due to high pressure and temperature, over millions of years.  A natural diamond crystal is very different from a faceted diamond as the rough shows no brilliance or shine but is rather a dull crystal called macle. Inclusions, i.e, small crystals, feathers or needles, are  clarity features of diamonds. Some clarity characteristics can be cut away during the manufacturing process and some can be positioned within the finished diamond in a way so as not to affect its appearance or durability.

 

While precise cutting and faceting can considerably improve a diamond's value, treatments have been devised to further improve its appearance. A few of these treatments are accepted by the diamond  gems industry and we will discuss them here.

 

Clarity Enhancement:

 

1. A - Laser Drilling

 

Since the early 1970s, diamond manufacturers have used lasers to drill tiny tunnels - thinner than human hair - into diamonds to reach dark inclusions. This process uses a carbon dioxide laser to heat a tiny area of the diamond until the inclusion evaporates .

 

A laser drill hole makes it possible to gain access to  the inclusions which can then be etched out with acid. This process lightens a dark inclusion thus  making the diamond more marketable. The disadvantage of this process is that when filled with foreign material, the visibility of the inclusion becomes more prominent.

 

Identification

 

Laser drill holes can be detected by careful examination under a microscope. Higher magnification is often necessary. Laser drilling can, in some cases, improve the clarity grade although the drill-hole itself becomes a clarity characteristic. This treatment of a faceted diamond does not impact durability of the stone.

 

Laser drill is distinguishable from etching channels - natural, hollow, tube-like features present in some diamonds - by the fact that laser drill holes are circular in cross-section, while etch channels are square, triangular or hexagonal.

 

1. B - Internal Laser Drilling

 

A variation on laser drilling is called internal laser drilling. It's a technique that uses a laser to expand cleavage or create a new cleavage between inclusion and surface of a crystal. This allows for the introduction of a bleaching solution resulting in the lighting of any  dark inclusion, making it less visible.

 

Identification :

 

The cleavage created by this procedure is more natural looking than a traditional laser drill hole. When you examine a diamond treated with ILD under magnification,a step-like series of tiny cleavages is visible. These wormhole-like channels are definite signs of ILD Treatment.

 

2. Fracture Filling

 

The Yehuda treatment, invented by Zvi Yehuda in the early 1980’s, is a  controversial treatment in the diamond industry. Inclusions in some diamonds can be treated by this method substantially increasing the clarity and value of the diamond.  The term  “Fracture-filled” is sometimes used  to describe these diamonds.

 

The Yehuda treatment involves insertion of a particular liquid, at high pressure, into the diamond inclusion, for example, into a feather.  Although this reduces visibility of the inclusion , it also makes the stone less durable and it cannot withstand the cutting and setting process involved in making jewelry. This process is not permanent. The heat from a jeweler’s torch or acid boiling will alter the glass filler and possibly destroy the stone  completely.

 

 

 

Identification: 

 

One indication of this treatment is  the flash effect seen in these treated stones. The typical blue or pink flashes are easily visible by rocking and tilting the diamond. Examination under a microscope will sometimes show iridescence and the feature become a permanent characteristic of the diamond. Gemological labs do  grade laser drilled stones and report the drill-hole as a clarity characteristic. Disclosure from wholesaler to consumer is compulsory.

 

Disclosure:  Although GIA doesn’t grade such treated diamonds, other Gem testing Labs do grade them with the condition of Disclosure. 

 

Colour Enhancement

 

IRRADIATION:

 

Diamonds that are naturally colored are so due to natural irradiation during their formation.  A diamond undergoes artificial irradiation to impart color  or to alter its color.   Alan Hodgkinson notes that coloration experiments using radium salts were conducted in the early 20th Century.  A new generation of radiation sources were used for diamonds and other gemstones.

Irradiation produces blue, green, and dark green colored diamonds.

 

Identification

 

To detect Irradiation treatment in diamonds is quite difficult for most gemologists and can sometimes be a challenge for the laboratory as well, as this modern technique of irradiating diamonds leaves little or no Color zoning and no radioactivity.

 

There are regulations on Diamond Irradiation though, specifically, how much amount of radioactivity is allowed on Diamonds and Gemstones.

 

Color modifying irradiation treatment usually comes after cutting & polishing of the diamond. Unfortunately, irradiation  colors are sensitive to heat. Technicians use cold running water to prevent color changes during the irradiation process, which generates a lot of heat.  One disadvantage of this process is that the heat from jewelry repairs, recutting or repolishing might also change the color of a diamond that has undergone irradiation.

At Jinas Jewels, we ensure diamonds used in our designs are of the highest quality.

Our founder, Jinagna Shah, is a jewelry designer, certified gemologist and certified jewelry appraiser. Please contact us at Jinas Jewels to get your jewelry appraised.