A deep blue with golden inclusions of pyrites which shimmer like little stars. This opaque, deep blue gemstone has a grand past. Reputedly brought to Europe by Alexander the Great the colour was referred to as 'ultramarine', which means something like 'from beyond the sea'.
The ultramarine of the great renaissance painters is nothing other than genuine lapis lazuli. Ground up into a powder and stirred up together with binding-agents.
Lapis lazuli is an opaque rock that mainly consists of diopside and lazurite. It came into being millions of years ago during the metamorphosis of lime to marble. Uncut, lapis lazuli is matt and of a deep, dark blue colour, often with golden inclusions and whitish marble veins. To see the colour properly, dealers in the mountains wet samples of raw lapis, with whatever water comes usefully to hand.
The small inclusions with their golden shimmer, which give the stone the gleam of a starry sky, are not of gold as people used to think, but of pyrites. Their cause is iron. The blue colour comes from the sulphur content of the lazurite (remember the colour of Copper Sulphate from your Chemistry lessons?) and may range from pure ultramarine to a lighter blue. The best raw stones still come from the steep Hindu Kush in the north-east of Afghanistan.