Expert advice on watches and jewellery
Coloured diamonds have been attracting the interest of jewellery connoisseurs since the 1980s, when pink diamonds were discovered in the Argyle mines of Australia. But their popularity has skyrocketed in the past few years, thanks to media coverage and celebrities wearing them. Who can forget the six-carat pink diamond ring worn by Jennifer Lopez during her short-lived engagement to Ben Affleck?
Coloured diamonds come in all sorts of hues, with pink being the most popular, says Terry Chu Yin-yee, deputy director of Sotheby's China and Southeast Asia. Chu says red and green diamonds are rare and valuable, and usually come in sizes less than one carat. Pink diamonds come in several carats. They're the most sought-after colour because they suit most complexions. Yellow diamonds have been around longer than pink varieties and generally are more affordable.
Coloured diamonds command higher prices per carat because they're rarer than their colourless counterparts. A pink or blue diamond can cost several times more than a white diamond of the same size. Criteria in choosing coloured diamonds are similar to white diamonds, but emphasis should be placed on the colour, while other factors are less important. 'The key is to choose a colour that you like, which complements your style and personality,' says Chu. Although colour is a matter of preference, consideration should also be given to the gem's preserving and resale value. Look for stones with vivid and intense colours, with an even hue and saturation. Popular cuts include round brilliant, oval, cushion and princess, all of which should bring out the natural colour of the gem if cut properly.
Carat weight is less important when it comes to judging coloured diamonds. For example, a 0.9-carat fancy vivid green diamond was bought for US$736,111 per carat in 1999, while a 0.95-carat red diamond was sold for US$926,000 at a Christie's auction in 1987, which remains a record price per carat for a gem sold at auction.
Before buying a coloured diamond, it's paramount to obtain certification from professional gemological laboratories. Unlike regular diamonds, coloured ones are prized and graded based on the presence of colour. The Gemological Institute of America grades coloured diamonds into nine categories: fancy vivid, fancy intense, fancy deep, fancy dark, fancy, fancy light, light, very light and faint. Fancy vivid is considered the most precious. Another laboratory, Gubelin, grades coloured diamonds by their carat weight, cut, polish and symmetry. It states whether the diamonds graded are natural, or how they have been treated otherwise.
