Usually when goods are flawed, we expect their value to drop, but it’s the exact opposite for diamonds. Ironically, it is imperfections that impart colour to diamonds – and these “fancy” diamonds are some of the most sought after in the world.

Diamonds are made of carbon atoms organised in compact structures. Clear, perfect diamonds sparkle because light reflects off their internal surfaces. Of course, these diamonds are valuable.

However, when diamonds host impurities, or are subjected to intense pressure, they can develop distinctive colours. Coloured diamonds are extremely prized for their beauty and rarity, and can be several orders of magnitude more expensive than clear diamonds.

So it’s no surprise the world was astonished when the Western Australia-owned Lucapa Diamond Company announced the discovery of the Lulo Rose this week. The 170-carat rough pink diamond, found in Angola, is the second-largest pink diamond ever discovered.

Few and far between
Coloured diamonds represents only 0.01% (one in 10,000) of diamonds mined in the world. Natural yellow and brown are the most common and, as you might expect, are therefore not overly expensive.

However, blue, green, violet, orange, pink and red diamonds are extremely rare and exist in minute quantities. These are truly coveted.

Ultra-rare coloured diamonds have been sold for record-breaking prices. The Pink Star, weighing 59.6 carats (about the size of a strawberry), is the most expensive diamond ever sold, for a staggering A$94.2 million.

It’s worth mentioning the Pink Star originally came from a diamond weighing in at 132.5 carats. More than half of its weight was lost in the process of cutting and polishing the stone – a process that took 20 months.

At 170 carats, it’s quite possible the Lulo Rose, if auctioned, could become the most expensive diamond in history.

The only pink diamond larger than it is the Daria-i-Noor (185 carats), which is the centrepiece of the Iranian crown jewels, and has never been for sale.

Read more: https://theconversation.com/perfectly-imperfect-the-discovery-of-the-second-largest-pink-diamond-has-left-the-world-in-awe-what-gives-diamonds-their-colour-187852