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Top 5 most expensive diamonds: No. 1 – The Koh-I-Noor

By Frank

Highly experienced diamond polisher who loves to share his knowledge with you. Continues to stun his colleagues with interesting - or simply bizarre - facts about diamonds and gems.

July 12, 2017

The most expensive diamond in the world is The Koh-I-Noor. This is an oval 109 carat diamond with a weight of 21.6 grams. It’s the main diamond of the British Crown Jewels, known from the crown. The stone is literally priceless. Insurance is therefore not possible. Talking about expensive… Currently, the Koh-I-Noor is on exhibition in the Tower of London together with the other crown jewels of Great Britain. During the biggest part of its long history, the Koh-I-Noor was the biggest diamond in the world.

Our Darling

Many people mention Royal Coster Diamonds and the Koh-I-Noor in the same sentence. Why is that? Upon its arrival in England in 1849, the diamond weighed 186 carats. In 1852, the British Royal House decided they wanted the most expensive diamond in the world repolished. Prince Albert, Queen Victoria’s regent, approached Royal Coster Diamonds for this noble task. Even back then, our expertise and craftsmanship where already well-noticed. Because our task to polish this famous diamond was so extraordinary, we dedicated more than just this article about it. Read more about the history of the Koh-I-Noor.

the koh-i-noor in the british crown


Royal Coster Diamonds recut the Koh-i-Noor to about 108.93 carats so the Royals could also wear it a bit more easily. Queen Victoria mostly wore the diamond in a brooch. Later it was set in the State Crown, worn by Queen Alexandra and Queen Mary.

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