Tiger's eye moves. Turn a piece in your hand and the golden band of light across it slides along the surface, brightening and darkening as it goes. That effect is chatoyancy, and it is the reason this stone has been valued for thousands of years. The cause is a mass of parallel fibres inside the stone. Light reflects off them as a single band rather than scattering, and because the fibres run one way, the band only shows at the right angle.

The material began as crocidolite, one of the fibrous asbestos minerals. Then the fibres were slowly replaced by silica, so that what is left is a quartz in the exact shape of the fibres that were there before. None of the original asbestos remains, which is why polished tiger's eye is safe to handle, wear and keep. That substitution is also why the fibres survive at all. Left in its original state the material would have degraded; locked in quartz it has lasted millions of years.

It sits at six and a half to seven on the hardness scale, which makes it tough enough to carry and wear, and it takes a mirror polish. Most of what reaches the market comes out of South Africa, where the deposits at Prieska are the largest known, with further material from Australia, India, Brazil and Namibia. 

There are two close relatives worth knowing. Hawk's eye is the same stone at an earlier stage of the replacement, with the blue-grey colour of the original crocidolite still in it. Pietersite is a rarer, more broken-up version in which the fibres sit at different angles, which is why it flashes in patches rather than in a single band.

Traditionally associated with

Tiger's eye is one of the stones with a genuinely long history of being carried, and the tradition sits with it rather than with its appearance. 

It is traditionally associated with courage and with protection in dangerous work. This symbolism has led to a claim that Roman soldiers wore it into battle, although there has been no archaeological evidence for this.

What is certain however, is that the stone has been worked and worn for a very long time, and that the courage association has followed it just as long.

How I'd keep it

Hardness makes this one of the more forgiving stones in the shop. Warm water and a little mild soap are fine, and it can be dried with a cloth and put back. Keep it away from acids, bleach and household cleaners. 

The one thing it does not like is being dropped, because the parallel fibres mean it can break along a plane rather than chipping, so a rough piece on a shelf wants a spot it will not be knocked from. It does not fade in sun. A piece on a sill is worth turning now and then so the band catches the light.

What to watch for

Dyed material is common. Tiger's eye is regularly stained and sold with a strong red or blue colour, which sits in the softer areas of the stone and can be seen in the cracks. The test for the real thing is the band. It should shift as you turn the piece, not sit flat. Reconstituted material pressed from powder is also sold, and it holds together with visible grain and no real sheen, although this is not a fake - it is genuine Tiger's Eye, just reconstituted.

Genuine rough tiger's eye is uneven, with the golden band often running across only part of the face and grey-brown matter around it.

In the shop

Rough Tiger's Eye is available from £10, and the pieces are one-offs, so the stone in each photograph is the one that arrives. We also have a Tiger's Eye Slab for £5. If you would rather wear it, there is the Tiger's Eye Ring With Leaf Detail at £60.