Photography: Tiffany & Co.
Coloured diamonds are all the rage these days, but do you know enough beyond the fact that yellow diamonds are the most readily available among the fancy-coloured stones, while the pinks are very rare?
They come in a rainbow spectrum of colours.
Coloured diamonds occur naturally in blue, brown, pink, purple, orange, yellow or even green. There are 27 hues in all, as different colours may be present in one stone. The spectrum ranges from pure yellow, to greenish blue, to reddish purple, to orangey-red. According to the Gemological Institute of America (GIA), the geological conditions required to yield these colours are rare, making diamonds with distinct and naturally occurring shades scarce and highly prized.
Pink diamonds are not just rare, they are extremely rare.
Out of all the diamonds mined in the world, 40 per cent are poor quality and only suitable for industrial use, while the next 40 per cent are gem-quality white and off-white diamonds, says Tay Kunming, director of Far East Gems & Jewellery and a course trainer at the Far East Gemological Institute. Among the remaining 20 per cent that are gem-quality coloured diamonds, 99 per cent are brown and one per cent represents all the fancy, fine colours. Out of these exceedingly rare fancy-coloured diamonds, only one per cent is pink.
You can't have the red.The rarest of them all is the red diamond, but the colour is so impossibly rare that it is not commercially available. GIA states that its records show that over a 30-year period from 1957 to 1987, there was no mention of a GIA lab report issued for a diamond with "red" as the only descriptive term. One of the most famous red diamonds is the 0.95-carat Hancock Red, which was sold for $880,000 in 1987. It was the most expensive per-carat gemstone ever sold at an auction – at a cool $926,315 per carat, eight times its pre-sale estimate.
Fancy-colour diamonds are evaluated less for brilliance and more for colour intensity.
Shades that are deep and distinct are rated higher than the weak or pale ones. The GIA describes colour in terms of hue, tone and saturation. Hue refers to the diamond's characteristic colour; tone refers to the colour's relative lightness or darkness; while saturation refers the colour's depth or strength. Using highly controlled viewing conditions and colour comparison measures, a diamond grader selects one of 27 hues, then describes tone and saturation with terms such as "Fancy Light", "Fancy Intense" and "Fancy Vivid."
You could possibly pass off an off-white diamond for a yellow diamond.
Everyone knows that for white or off-white diamonds, D colour is the best while the XYZ range of yellow-tinged hues is considered the poorest. However, when the yellow increases in intensity, it is considered to be in the fancy-colour category, which also means an enormous price jump. One industry secret is that you could buy an XYZ-colour off-white diamond, which would look almost similar to the lowest-graded colours in the Fancy Yellow range. In fact, for a trained eye to tell them apart accurately, they would need to refer to a master set of diamonds.
Natural black diamonds aren't actually black.
Natural black diamonds are actually brown diamonds so heavily included with dark particles that they appear black, says Kunming. Most of the even-coloured black diamonds used by jewellers have been treated by irradiation, heat or pressure to turn white or yellowish diamonds into a green so dark that it appears black, but not opaque.
