- published: 14 Nov 2009
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Tiger's eye (also called tiger eye) is a chatoyant gemstone that is usually a metamorphic rock that is a golden to red-brown colour, with a silky lustre. A member of the quartz group, it is a classic example of pseudomorphous replacement by silica of fibrous crocidolite (blue asbestos). An incompletely silicified blue variant is known as hawk's eye.
The gems are usually cut en cabochon in order to best display their chatoyancy. Red stones are brought about through gentle heat treatment. Dark stones have had their colours improved and been artificially lightened using nitric acid treatments.
Honey-colored stones have been used to imitate the much higher valued cat's eye chrysoberyl (cymophane), but the overall effect is unconvincing. Artificial fibre optic glass is a common imitation of tiger's eye, and is produced in a wide range of colours. Tiger's eye comes primarily from South Africa and east Asia.
Tiger iron is an altered rock composed chiefly of tiger's eye, red jasper and black hematite. The undulating, contrasting bands of colour and lustre make for an attractive motif, and it is mainly used for jewellery-making and ornamentation. Tiger iron is a popular ornamental material used in a variety of applications, from beads to knife hilts.