5 Things You Didn't Know About Diamonds

De Beers Diamond Jewellers invites us to an exclusive masterclass in Hong Kong where Andrew Coxon, president of the De Beers Institute of Diamonds, shares some surprising facts about these precious stones

When a rough diamond is transformed, it loses almost half its weight

Naturally beautiful rough diamonds are rarer than naturally beautiful polished diamonds.

You can make any diamond look pretty after a good polish, but you'll sacrifice half of its weight in the process. In some of the De Beers mines, such as the ones in Namibia, you find naturally beautiful rough diamonds washed up along rivers.

Diamonds are formed 300 miles under the Earth’s surface

Above As president of the De Beers Institute of Diamonds, Andrew Coxon is an expert in diamonds with over 40 years of experience at the De Beers group. (Photo: Courtesy of De Beers)

Some diamonds have an easier journey to the Earth's surface, and this impacts the way a diamond looks when it's polished. Some polish up wonderfully, and others don’t. It depends on the movement of the tectonic plates, as well as the region's volcanic activity.

Australian diamonds, for example, often look like they’ve been overcooked. Namibian diamonds, despite travelling the same distance, pop out of the ground looking brand new. It takes years of experience to know which areas produce the best diamonds.

25% of the world’s diamonds are found in rivers and lakes

This is because tectonic plates push them to the surface within a lava-like rock called kimberlite, which is fry-able when exposed. When it reaches the Earth's surface it hardens and crumbles releasing the diamond within, which is then washed down rivers and valleys, often into the sea.

The formation of new diamonds stopped happening over 800 million years ago, and the oldest mined are up to 3.4 billion years old.

There is such thing as ‘Diamond Luck’

Above Photo: Courtesy of De Beers

Some people are just lucky when it comes to diamond mining. Eira Thomas, for example, began working with her father who is a geologist immediately after graduating from university. She said that one day, they were drilling on the banks of a frozen lake, and she found the best kimberlite diamond mine in Canada.

In the drill sample they found a two-carat diamond crystal. In 70 years of drilling by De Beers in South Africa, we've not even found a one-carat diamond in a drill sample. She has got, what we in the business call, ‘Diamond Luck’.

Diamonds are nature's hardest mineral

Mohs scale is used to measure the hardness of a mineral by its resistance to scratching. Diamonds measure 10–rubies and sapphires are nine. But a diamond is 400% harder–four times harder! It's a magical mineral and there's nothing else like it on Earth–all the atoms are the same distance apart.

Curiously, electricity won't pass through a diamond and it won't hold heat. That's why when you touch one it always feels cold.

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Watches & Jewellery Jewellery De Beers Andrew Coxon Diamonds Jewellery Facts