Natural color diamonds in the marketplace today, are beautifully rare treasures, authentic creations within nature which formed deep within the Earth millions of years ago and only now are becoming visible at the Earths surface. Natural color diamonds are valuable because the presence of color is an entirely natural process ensuring every stone is one of a kind. The NCDIA and most experts feel that it is most important to have your natural color diamond tested and issued a color diamond grade report by a reputable major gem laboratory.

In reviewing such a report for a natural color diamond, it is critical that the word "natural" be displayed as the origin of color. If a laboratory cannot determine the natural color, the words "undetermined" will appear on the grading report and you might wish to seek a second analysis by another reputable source. If any laboratory report indicates the word “Treated” it means they detected HPHT or some other treatment that was applied to the jewel and this will significantly lessen its market value.

Common known types of treatements

• HPHT – the most widely known treatment for diamonds, combining high pressure and very high temperature. HPHT can make a stone more colorless, or can produce blue, yellow orange, yellow green, pink or brown color in diamonds, depending very much on the diamond selected for treatment. This process in some cases mirrors the conditions in which diamonds are formed in nature, but is detectable by most major gem labs. Laboratory reports would indicate "HPHT" as the "Treated" designation.
• CVD – By infusing CO2 into the plasma of an existing diamond, Chemical Vapor Deposition produces brown, colorless, faint pink, blue and black. Lab reports will indicate "CVD".
• Irradiation - radiation can cause a diamond’s color to change. Most commonly found colors in irradiated diamonds include green, blue and black diamonds. Lab report will show "Irradiated."
• Surface Coating - thin layer of a colored material is deposited on the diamond in order to change its original color. Lab report will indicate "Coated".

Independant Gemmological Laboratory Reports

The NCDIA reccomends that you always ask to see an independant lab report to assure that you know exactly what the origin of color is on your stone. Although treatments may sometime enhance the color of the stone, they almost always decrease the value of the stone.


Learn about Grading Natural Color Diamonds