Whether they’re sparkling on your finger, or hard at work on the end of a drill bit, diamonds are one of the world’s most sought-after minerals. Here are some of our favourite facts about these beautiful, ancient and super-strong stones. How diamonds were created Diamonds are made from carbon, and the pressure put on the carbon atoms 100 miles under the Earth’s surface causes them to bond in a unique way, giving them their stunning structure. Volcanic activity brought the diamonds closer to the surface. Beautifully strong The way the atoms bond also makes them incredibly strong. The diamond is the hardest naturally-occurring mineral in the world. However, artificial substances rhenium diboride, ultrahard fullerite and aggregated diamond nanorods are all harder, and will actually scratch a diamond. Are diamonds forever? The word “diamonds” comes from the Greek adamas, meaning indestructible. However, a poorly-cut diamond can crack or splinter. There could be a fault line inside the stone leading to a weakness. Their reputation for durability largely comes from the fact that they don’t scratch, but can scratch other hard materials. Mining for diamonds They may be 3 billion years old; but the earliest reference of them being traded is the 4th century BC, in India. Diamonds were mined in India until the 18th century when Brazil became the main source, and South Africa took over a century later. Today, they are mined globally; and Botswana, Russia and Canada are particularly productive. An average of 250 tonnes of earth needs to be mined to find a single one-carat diamond. Just like the real thing Due to concerns about the ethics of mining and the impact on the environment of some methods, synthetic diamonds have become popular. Diamonds created in a laboratory are made from the same material and look identical to the real thing. Stones of many colours Clear diamonds (called “white diamonds”) are the ones most of us picture; however impurities in the stone can cause some beautiful colour variations. Diamonds come in a whole spectrum of colours, with yellow being fairly common, and red and blue the most rare. The largest diamonds The Cullinan Diamond was found in South Africa in 1905 and presented to King Edward VII. Originally the largest diamond ever found (at 3,106 carats), it was cut into over 100 diamonds, some of which were set into the Crown Jewels. The largest cut diamond is The Star of India, weighing 530 carats. Bonus carat fact: it’s thought the word comes from “carob”, as these beans used to be used for measuring weights. A carat weighs 0.2 grams. Diamonds in engagement rings It’s believed that the first diamond engagement ring was given to Mary of Burgundy by Archduke Maximillian of Austria in 1477. However, it was a 20th century advertising campaign by diamond giant de Beers that cleverly made diamonds synonymous with romantic proposals. Their slogan “Diamonds are forever” was created in 1948. Diamonds in watches In high-end mechanical watches, jewels are used to prevent parts of the movement from rubbing together and wearing out. This is usually synthetic rubies in modern watches; however in the early days of watches, diamonds were sometimes used, as the jewels need to be hard to be effective. These days, diamonds are more often found on the dial or bezel of a watch. Other surprising places to find diamonds Because only around 20% of all diamonds mined are suitable for jewellery, the other 80% turn up in some unglamorous places. Because they are so tough, they’re used in cutting and grinding tools, such as drill bits. Diamonds were used in ancient China for sharpening axes. They also make great nail files! A few diamond myths Because diamonds were thought to give courage and strength, rulers of ancient cultures wore them into battle. The Romans thought they could ward off evil, and the Ancient Greeks believed they were splinters of fallen stars. In the Middle Ages, they were believed to cure mental illness or fatigue. If you know any other amazing diamond facts, please let us know!