Turquoise is ancient, yet again and again it finds itself back in fashion. Its shining sky blue is one of the most popular trend colours in the world of jewelery and fashion.

In many cultures of the Old and New Worlds, this gemstone has been esteemed for thousands of years. The oldest evidence for this claim was found in Egypt, where grave furnishings with turquoise inlay were discovered, dating from approximately 3000 B.C.  Turquoise is a copper aluminium phosphate with a hardness of 6, i.e. considerably softer than quartz.

 In Nature, it occurs in the whole range of hues from sky blue to grey-green, and it is mostly found in places where there is a high concentration of copper in the soil.  The blue colour is created by copper, the green by bivalent iron and a certain amount of chrome. Often, the material has veins or blotches running through it, which are brown, light grey or black depending on where it was found. These lively, more or less regular patterns are known as 'turquoise matrix'. The crystals are microscopically small and can hardly ever be recognised with the naked eye. As a rule, turquoise occurs as a fillung in veins or crevices, or in the form of nuggets. The most well known deposits are in the USA, Mexico, Israel, Iran, Afghanistan and China. The most beautiful turquoises, in a splendid light blue, come from deposits in the north of Iran. --gemstones.com