International diamond trade association committed to fostering and promoting the highest ideals of honesty and best practice principles throughout the diamond industry worldwide.
Independent Laboratory
Diamond grading laboratory that has no financial interest in the actual trade (buying and selling) of diamonds.
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.
International Diamond Council
International organisation founded by the World Federation of Diamond Bourses (WFDB)and the International Diamond Manufacturers Association (IDMA) to establish standard rules for diamond grading and nomenclature.
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’.
Indented Natural
The original skin of the rough diamond that remains after polishing and is indented into the body of a diamond, not confined to its surface. An indented natural can affect both the polish grade and the clarity grade of a diamond.
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.
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.
HPHT (High Pressure High Temperature) Treatment
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.