Polished Turquoise Cabochon

Turquoise has been one of the most popular gemstones for thousands of years.  It forms mainly in arid environments from the alteration or weathering of existing rocks rich in aluminium.  The main constituent in most commercial grade turquoise is a mineral called planerite. 

The colour of turquoise can vary depending on the amount of iron and other minerals present. It forms within existing rocks over thousands of years.

The dark spidery veins often but not always present are the remnants of the host rock in which it formed.

Turquoise is a relatively soft and fragile mineral that needs to be well looked after.  Stones can fade or change colour because of long term exposure to bright sunlight, acidity and even moisture from the skin.

The front of this turquoise stone has a vitreous lustre whilst the back is dull.  Dull means it absorbs light instead of reflecting it.