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Laser Drilling

by on June 11, 2013

We at Gesner Estate Jewelry do not sell diamonds that have been laser drilled. On the rare occasion that we acquire a diamond that has been laser drilled, that clarity enhancement will be disclosed to the buyer. These articles are here to help educate potential buyers to make the best possible decision with their gemstone purchasing.

Laser Drilling

Diamonds are specifically known as the hardest mineral and can hold a polish extremely well and retain their luster.  Its hardness contributes to its suitability as a gemstone.  Because it can only be scratched by other diamonds, it maintains its polish like no other and is well-suited to daily wear that is probably why they are the preferred gem for engagement or wedding rings.

But diamonds can sometimes be flawed by its own mineral in terms of carbon inclusions in the gem when, on its way up to the Earth’s surface, it sometimes encounters carbon at different stages of development and the dominant diamond encloses the carbon within itself. The carbon that is black can be seen under magnification and sometimes even to the naked eye in a cut and polished diamond.

This flaw is corrected by laser drilling, a process developed in the early 1960s by General Electric. The process is to drill into the diamond using a laser beam with a diameter that is 100 times smaller than a strand of hair. After drilling, the diamond is then boiled in acid under high pressure so that the acid reaches the black carbon through the laser-created entrance and in effect “bleaches” the carbon and turns it to white.

It is generally believed that the black carbon is actually removed, but nothing is ever actually removed from a diamond.  The process simply changes the color of the black carbon giving the perception to the naked eye that it has been removed.

Through laser drilling, the defect in the diamond is permanently corrected. The treatment  does not actually alter the diamond’s carat weight and conversely improves its clarity and sometimes the diamond’s perceived color becomes darker by one grade.  This is due to the absence of the black contrast in the diamond that absorbed the diamond’s natural color.

The Gemological Institute of America offers a full grading report of laser drilled diamonds as they consider the laser drilled diamonds to be permanently treated. However, it is GIA’s policy not to offer grading reports on enhanced diamonds because they do not consider the process as permanent.

Ironically, jewelers seem to lean more in preference to clarity enhanced diamonds than the laser drilled diamond believing that drilling makes a diamond unpure. On the contrary, the laser treatment allows the diamond to release its true brilliance without the visually disturbing black carbon.

Diamonds often have dark inclusions present, usually consisting of graphite or sulphide, or other iron-containing minerals. These dark inclusions become present in the diamond during its natural growth formation. For obvious aesthetic reasons, diamonds with visible dark inclusions are less desirable than those with light or transparent inclusions.

Diamonds with surface-reaching black inclusions are often deep boiled under pressure in strong acids, as the mineral inclusions described are all dissolved by these acids without affecting the diamond material itself. Deep boiling forces the acid deeper into surface-reaching cracks of the diamond, allowing more of the black material to be reached. But what happens when a dark inclusion is completely sealed inside the diamond? There are currently two known methods for reaching such inclusions, traditional laser drilling and Internal Laser Drilling.

TRADITIONAL LASER DRILLING

Laser drilling is the process of drilling a hole with a hot, high-power laser beam from a point on the surface of a diamond to a dark inclusion trapped within the diamond. The pulsed, focused beam vaporises a tiny channel, or ‘drill hole’, to the dark inclusion; this provides a conduit to the inclusion from the surface, and deep boiling in acid or bleach will remove the dark and cause the inclusion to be less visible. The drill holes themselves appear as fine, straight tunnels from the surface of the diamond to an inclusion.

According to internationally accepted rules for diamond certification, laser drilled diamonds are allowed to be certified because the treatment is permanent – it will not change or revert back to its original state. However, the treatment must be clearly stated on the certificate; laser drilling may improve the appearance of a diamond, but it also reduces its value.

INTERNAL LASER DRILLING (KM TREATMENT)

KM stands for the Hebrew phrase ‘kiduah meyuhad’, meaning ‘special drill’. Rather than burning a hole to a dark inclusion from the surface like with traditional laser drilling, a very hot laser is focused on the internal inclusion itself. The heat causes the inclusion to expand, and creates small channels from the inclusion to the surface. As with traditional laser drilling, once a channel to inclusion is created, the dark inclusion can be bleached out with a strong acid.

KM internal laser drill holes can vary in appearance. Some look slightly irregular worm holes, or step-like channels. Others appear with disc-like features, with irregular boundaries. In any case, careful gemmological examination will conclusively identify the treatment.

As with traditional laser drilling, the treatment of diamonds with KM internal laser drilling is permanent. Thus, KM drilled diamonds are also allowed to be certified, according to internationally recognised standards for diamond certification, but the treatment must also be clearly stated on the certificate as the treatment reduces a diamond’s value.

**This information has been taken from www.hubpages.com and www.dcla.com**

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