Corundum

Corundum is a highly durable and valuable mineral, known for being the base material for some of the most famous gemstones, including rubies and sapphires. It is composed of aluminium oxide and ranks 9 on the Mohs scale of hardness, making it one of the hardest minerals on Earth. While rubies are red corundum and sapphires come in various colours (except red), both share the same mineral composition. Corundum's brilliance, range of colours, and exceptional hardness make it a prized choice in fine jewellery.