What makes coloured diamonds so special? We spoke to the experts at the luxury British jeweller Boodles to discover everything you need to know about the covetable coloured stones...
1. They're sought-after because they're rare.
Fancy coloured diamonds are not as common as white diamonds, which adds to their appeal (and their value).
2. There's a big difference between a diamond that is slightly discoloured and one that is 'fancy' coloured.
"Beauty is always in the eye of the beholder, but everyone sees beauty when the colour is definite (e.g with yellow stones, when they are 'fancy' and not just tinted)," says Jody Wainwright, the director and head of gemstone sourcing at Boodles. The grading of coloured diamonds is complex, as every stone has a different depth of colour. They are ranked on a different scale to white diamonds (which are graded from D to Z) and are classed as 'coloured' if they are found to be more intense in hue. The coloured diamond scale grades from 'faint' and 'very light', through to 'fancy light', 'fancy', 'fancy intense', 'fancy vivid' and 'fancy deep' - although it's worth noting that the latter is less valuable than 'vivid' as the colour saturation is too great. This is then cross-referenced by colour (for example blue, bluish-green, blue-green or green). Diamonds have to reach a certain colour saturation before they can be classed 'fancy'.
3.The coloration of a diamond is the result of external influencers on the stone.
"The coloration in diamonds is caused by the addition of different elements and conditions," explains Wainwright. "For example, green diamonds are caused by natural irradiation; blue by the addition of Boron; and yellow by the addition of Nitrogen. The cause of pink and red diamonds is largely mysterious, though some evidence has found that high pressure and heat can result in the deformation of structure."
4. The coloration of a diamond has an enormous impact on its value.
Essentially, the brighter and more colourful, the better. "For example, a fancy orange-pink diamond might be less than half the value of a fancy purple-pink stone," says Wainwright. "Why? Purely because the purple boosts the pink, giving it a more desirable colour, while orange can take it towards a more brownish hue."
5. Red diamonds are the rarest.
Equally, they are the most expensive. "Green diamonds are not far behind this [in terms of rarity]," explains Wainwright. "But blues and oranges take the second-highest value."
6. The setting of a coloured stone is just as important as the stone itself.
"Coloured diamonds range from very subtle pastel hues through to intense and vivid colours, so the choice of which particular shade of gold – and there are many variations – will best complement the colour of the stone is important, as is the decision on which other gems to cast alongside," says Rebecca Hawkins, head of design at Boodles. "It's important to consider, for example, whether to add definition by contrasting it with pure white diamonds or to create a harmonious mood by mixing gentle nuances of colour. The aesthetic of the design needs to celebrate the coloured diamond without over powering it."
7. Buy carefully.
As with white diamonds, there are no papers authenticating the origin of a coloured diamond, which means it's even more important to buy from a trusted source, like Boodles, which has 218 years of experience. Unlike white diamonds, which are graded with very fine parameters, coloured diamonds need to be valued first-hand by an expert as there's such a wide scope within each category.
8. They were made to be seen.
It's all too tempting to store fine jewellery away where it can never be harmed, but coloured diamonds were made to be seen – so wear them. "If you are fortunate enough to have a quiver of coloured diamonds, I would wear them as and when you so desire," says Wainwright. Hawkins agrees: "Colour is naturally very evocative and imbues diamonds with a poetic quality, giving the effect of an imaginative and emotional style of expression. They can be both dramatic and dreamy, and I don't think should be reserved for any particular occasion – it is more about the wearer."