Coloured diamonds: how to buy

Once considered the “white” stone alongside red rubies, blue sapphires and green emeralds, coloured diamonds are now highly sought after by collectors and jewellery fans. Some of the rarer colours are considered investment grade stones and change hands for many millions of dollars. 

Even if your budget is more modest, you can still find plenty of beautiful, affordable coloured diamonds for sale. These are some of the key colours to look out for:

Pink diamonds

Pink diamonds are mysterious as scientists are unsure exactly how their colour occurs. Many of the world’s pink diamonds come from right here in Australia, mined in the Kimberleys. Ranging from palest pink to pink champagne, deep purple-pink and violet, the more intense colours typically command the highest value. One of the most famous pink diamonds is the 182-carat Daria-i-Noor, part of the Iranian Crown Jewels. Analysis suggests it came from a 400-carat stone mined in India around a thousand years ago.

Blue diamonds

Blue diamonds owe their beautiful colour to trace elements of boron. Vivid, pure blue diamonds are the most valuable, compared to grey-blue or green-blue. One of the most famous blue diamonds is the 45.55-carat Hope Diamond, believed to be mined in India and also thought to be cursed! It was last bought in 1949 by New York gem merchant Harry Winston, who donated it to the US National Museum of Natural History in 1958, where it’s displayed as part of a diamond necklace. It was last insured for $250 million.

Red diamonds

Red diamonds are among the rarest and most expensive gemstones in the world. They may cost hundreds of thousands of dollars per carat, and they’re so rare that it’s hard to find sizes larger than one carat. The biggest and most flawless red diamond ever found is the 5.11-carat Fancy Red Moussaieff Red Diamond, discovered in a river in Brazil. Purple-red colours are generally more valuable than orange-red or brownish-red.

Green diamonds

Green diamonds are the result of radiation from rocks containing uranium or thorium, though they’re totally safe. The green colour is often only on the surface of the diamond: it’s very rare to find uniformly green stones. The apple-green 41-carat Dresden Green diamond is one of the largest and most historic green diamonds, dating back to at least 1722. It’s thought to have been mined in Andra Pradesh, India.

Yellow diamonds

Also known as champagne diamonds, canary diamond and golden diamonds, yellow diamonds are the result of nitrogen being present when they formed. Their hues vary from brown through orange to greenish, but pure, deep yellow is the most sought-after shade. One of the largest yellow diamonds ever mined is the 342.57-carat lemon-yellow 26th Congress of the Communist Party of the Soviet Union, which is a raw (uncut) stone mined in Siberia.

Black diamonds

Also called carbonados, some natural black diamonds are thought to come from outer space as the result of an asteroid impact. The 67.50-carat Black Orlov or Eye of Brahma is one of the world’s largest, and like the Hope Diamond, is thought to bring bad luck. It was famously worn by actress Felicity Huffman at the 2006 Oscars. Buying coloured diamonds can be challenging if you don’t know what you’re doing. Coloured diamonds sometimes have their natural colours enhanced through processes such as irradiation or high pressure, and such stones are much less valuable than naturally coloured stones. Artificially created diamonds come in a range of colours as well, and their value also tends to be lower than that of natural stones.

Therefore it’s very important to get precious stones properly certified by an expert, so you can be sure you are getting the real deal. Options for buying loose stones and diamond jewellery include:

• Retail: this can be an easy way to choose from a range of stones and settings, but jewellers have many overheads that will increase the price of a diamond, such as rent and staffing costs. Retail margins can be very high, which may make it a less cost-effective option.
• Auction: buying coloured diamonds through a reputable auction house is one way to get a better deal, as goods sold through auction typically sell for a fraction of the retail price. You can buy brand new jewellery as well as heirloom pieces.

First State Auctions was established in 1995 and is owned by gemmologists and diamond graders. Coloured diamonds in all shapes colours and sizes often feature in our auctions and we guarantee the authenticity of all our coloured diamonds and other gemstones. You can buy something that’s not only beautiful, but a wonderful bargain.

Please feel free to contact us if you would like to talk to our experienced diamond graders.