A beautiful opaque stone which gives its name to the colour, turquoise was so named by the Venetians who bought the stones from Turkish traders. In fact, it came from Persia, where the best quality stones are mined--those of a pure, unblemished sky blue. An ancient gem, it was used by the Ancient Egyptians, and was thought to bring good fortune and general well-being to the wearer. More recently it was used extensively in nineteenth century jewellery, and was symbolic of true love. For this reason Queen Victoria gave her bridal party gifts of turquoise brooches.
Turquoise is a copper aluminium phosphate - copper being the primary cause of its pleasing blue colour. It has a microscopic crystal structure, which makes it ideal to be fashioned into smooth cabochons rather than faceted. The material takes a good polish and has an appealing waxy lustre to the surface. The most desirable turquoise specimens display a highly saturated blue hue, by which the colour itself is now defined, though it can also be found with hints of green or grey.
It is an opaque gem, and is often formed in what is called matrix, a black or brown veining derived from the host rock in which the gem forms. In fine jewellery, unblemished sky blue turquoise is the ideal, although regularly patterned matrix turquoise is also sought-after.