Having discussed diamond colour in the 4Cs section, we explained that a colourless diamond is the most desirable. This statement is absolutely true when limiting our discussion to white diamonds, but it is important to understand that diamonds do occur in many colours.
The general consensus is that the closer a diamond is to being colourless the more valuable it is. The exception to this is those diamonds that are “Fancy Colours”.
They may range from vibrant yellows (canary), browns (cognac), blues, greens, oranges, violets, and pinks to the rare red diamond. The various colours are influenced by the presence of trace mineral elements in the carbon structure of the diamond.
Aluminum induces the blue colour, manganese attributes for the pink colour and traces of nitrogen account for yellow colour.
Value for a fancy colour diamond is directly related to how rich and strong the hue is, as well as their cut, carat weight and clarity. The cost of fancy coloured diamonds is directly related to their rarity, size and intensity of colour, with less importance being placed upon the clarity.
The Colour Spectrum for fancy coloured diamonds evaluates the hue, tone and saturation of the diamond colour. It assigns colour valuations as faint, very light, light, fancy, fancy dark, fancy intense, fancy deep and fancy vivid in varying degrees of saturation from lower to higher.
Irradiation of a diamond at the lower end of the colour grading scale, is a post World War II diamond treatment that may provide a colour change equivalent to that of a fancy yellow or fancy green colour. Although these enhanced colour diamonds may appear as beautiful as their natural colour diamond counterparts, their pricing is less than a natural colour diamond and the irradiated treatment must be disclosed.
One method of enhancing the clarity of a diamond involves filling fractures with substances that match the optical properties of a diamond. Yehuda diamonds are fractured filled diamonds and should be disclosed as such. Fracture filling is not a permanent enhancement treatment (fill material may be affected by exposure to heat) and cannot be accurately clarity graded.
Laser drilling may change a dark inclusion to a less visible inclusion (to the unaided eye). Laser treatment is considered a permanent treatment and an accepted practice in the jewellery industry, without affecting the clarity grading or diamond brilliance.