A to Z of Gemstones: T: Turquoise


Crystal System: Triclinic

Moh's scale of hardness: 5-6

Lustre: Waxy

Birthstone: December

About: Turquoise is a copper mineral valued for it's vibrant colour, the blue colour is due to the presence of copper and the green is due to iron.  Turquoise is opaque to slightly translucent and the colour varies from deep sky blue, through to blue, greenish-blue and green.  It may have veins and mottling of black and brown.  Pyrite inclusions may also be visible.

Origin: The main sources of Turquoise include: Iran, Egypt, USA (Nevada, Arizona & California), Chine, India, Mexica and Russia.  

Use in jewellery: Turquoise is cut into cabochons and beads for use in jewellery.  It is best to avoid contact with perfumes and cosmetics which may discolour the turquoise.

Treatments, synthetics and imitations:  Nearly all Turquoise is waxed to improve the lustre and minimise breakage.  Stabilisation is also common, where resin or glass of the same colour is used to fill any cracks in the material.  Turquoise may also be dyed to enhance the colour.  Reconstructed turquoise made from fine fragments of material bonded back together with resin.   Reconstructed turquoise can be distinguished by it's speckled appearance.