The sapphire is a precious variety of the mineral corundum, best known in a deep blue, though it also occurs in pink, yellow and green (every colour except red, which is called ruby). The sapphire owes its classic blue to traces of iron and titanium. Like the ruby, it is exceptionally hard and durable, so it is ideal for everyday-wear rings. Historically the sapphire symbolised wisdom, fidelity and the heavens, prized by kings and clergy; a famous sapphire adorns the British crown too. In jewellery the most valuable are the velvety-blue 'Kashmir' sapphires. The sapphire lends a look a noble, restrained depth of colour.
