“Diamonds Are Forever” is often heard and was immortalised by shirley Bassey's title song of the James Bond movie of the same name. This is true! Diamond is the world’s hardest natural material and diamonds are the most durable and ever-lasting material on Earth, so, yes, diamonds really are forever thanks to their durability, or rather, the extraordinary stability, hardness and toughness of diamonds.

Stability refers to how well the gemstone resists light, chemicals and heat; hardness describes its resistance to scratching; and toughness describes how hard it is to chip or break the gemstone. Diamonds have excellent stability and hardness, and are very tough, making them all round incredibly durable.

Diamonds are very heat resistance. Diamond has an extremely high melting point of 3,820 degrees Kelvin. This is unsurprising given the very high temperatures and pressures under which tey are naturally formed. They are also very stable to light and are chemically inert. These features mean that diamonds have an extremely high stability.

It is the best heat conductor of all natural elements, due to its high lattice density (number of atoms per unit volume).

Diamond is the hardest of all known natural materials. It measures the maximum 10 on the Mohs scale, which tests material hardness by how easily a mineral can be scratched. Diamond is so hard that the next hardest mineral on the Mohs scale, corundum – a family containing both sapphire and ruby, is four times softer than diamond.

Because softer minerals cannot scratch harder minerals, and diamonds are the hardest known natural material, they cannot be easily scratched, making them perfect for setting into jewellery. However, a harder diamond can scratch a less hard diamond, and so different diamond jewellery pieces should be kept separately in cloth pouches in a jewellery box.

Although a diamond is very tough and will not easily break, a diamond can be broken, or cleaved, if it is hit very hard with a blow that splits it along its crystalline structure. Ruby, sapphire and alexandrite are all tougher gemstones than diamond.

To enhance diamond's natural toughness, a good quality cut diamond will have its outer rim (girdle) left thick enough to prevent chipping. and its cutlet (the pointed end of a diamond) not so pointed that breakage could occur during the setting process.

So now you know what makes a diamond inspire a song like "Diamonds Are Forever", why not add some to your fine jewellery collection and make sure they are truely everlasting by passing them onto future generations. Start a family heirloom tradition!