Natural color diamonds are exquisitely rare treasure, formed at high-pressure high-temperature conditions existing at depths of 140 to 190 kilometers (87 to 120 mi) in the Earth’s mantle.Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. It is considered to have the highest hardness and thermal conductivity of any bulk material, and it is because of those properties that diamond is determined as the major industrial application in cutting and polishing tools.

Natural color diamonds are valuable because every stone is one of a kind due to the presence of color in an entirely natural process. It is important to have the natural color diamond tested and issued a color diamond grade report by a reputable major gem laboratory to ensure the credibility and authenticity of the stone.

A report for a natural color diamond contains the word “Natural”, if the natural color diamond is determined to have not undergone any treatment or enhancement. If the laboratory cannot determine the natural color, the words “Undetermined” will appear on the grading report. A second analysis by another reputable source is therefore suggested. If the laboratory report indicates the word “Treated”, it means that some treatment or enhancement as applied to the jewel and this will significantly lessen the jewel’s market value.

Common known types of treatments include HPHT, combining high pressure and very high temperature. This can alter brown diamonds into yellow or even colorless stones. Laboratory reports would  indicate “HPHT” as the “Treated” designation. Chemical Vapor Deposition or CVD produces brown, colorless, faint pink, blue and black. Lab reports will indicate “CVD”. Irradiation can cause a diamond’s color to change to include green, blue and black. Lab reports will show “Irradiated”. A thin layer of a colored material is deposited on the diamond in order to change its original color is known as Surface Coating. Lab report will indicate “Coated”.

It is recommended by authorized diamond organizations and experts to always seek for an independent lab report to ensure that exact origin of color of the stone. Treatments may sometime enhance the color of a stone, however they almost always decrease its value.