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Industrial Grade Diamond

Diamond usually not polished as a gemstone, as it does not meet the minimum quality criteria for grading. Industrial diamonds are very heavily included, lacking the transparency, brilliance and life that a gem quality diamond must exhibit. Industrial diamonds are somtimes used in their rough diamond form in jewellery.  Industrial diamonds are very useful for tools, drills, lasers, abrasives, and other such uses. Only approximately 20% of mined diamonds are of gem quality.

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Ideal Cut

Term often used for a round brilliant cut diamond that is believed to be excellent across the board for proportions and overall make.  There are many different ‘ideal cuts’, the most famous being the Tolkowsky Ideal Cut. The range for ideal cut diamond parameters can often be very broad, so care must be excercised in labeling a diamond as ‘ideal cut’.

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Hue

Occasionally ‘colourless’, or Cape Series diamonds will have a visible negative tint of brown or grey. These diamonds are graded on the same scale of color saturation as Cape Series diamonds, but will state the hue on the certificate. Diamonds with brown, grey, or ECG hue are of lower value than those with no hue. Click here to see where to find hue on a Diamond Certificate.

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HPHT (High Pressure High Temperature) Treatment

Treatment to change or artificially enhance the colour of a diamond. Certain types of diamonds are subjected to extreme heat and pressure conditions in a laboratory, which rearranges their atomic structure and thus alters their colour. Click here to learn more about HPHT treated diamonds.

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Hot Laser Inscription

The use of a laser beam to write a number or customised personal message on the girdle of a diamond, generally for identification purposes. Hot laser machines operate at a higher wavelength, and unlike cold laser inscription can penetrate into and thus damage the diamond; penetration can result in chips and fractures. Click here to learn more about diamond laser inscription.

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Hearts & Arrows

Describes a pattern that appears in some round brilliant cut and square cushion cut diamonds that have a certain parallelism and symmetry. When viewed from above through the crown, the pattern is a series of eight arrowheads. From below through the pavilion, the pattern appears as eight heart shapes. Hearts & arrows does not mean that a diamond is ideal cut, only that it is symmetrical.

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Heart Cut

Diamond cut or shaped into a heart, with a cleft in the wide end, and a softly tapered point at the narrow end.