Turquoise is a magnificent opaque blue stone, sometimes blue-green going to green.
It takes its name from Turkey, a country it was thought to have come from. We will learn later that it came from Iran, Turkey being at the crossroads between East and West it was in fact the center of resale of Turquoises to the West.
Turquoise has been used on the most beautiful jewelry since ancient times, especially in Egypt where it was mined in the mines of Sinai.
The most beautiful Turquoises therefore come from Iran, near Nishapur. They are a deep sky blue given by its rich copper composition. Later, in the 19th century, Persian Turquoises were scarce, so people turned to the southwestern United States for supplies. American Turquoises contain more impurities, they are traversed by black and brown veins of matrix (their mother rock).
The color of Turquoise can vary over time, changing from blue to a shade of green. Being a stone composed of water molecules, the latter shows green undertones when dehydrated.
Completely dehydrated, we call it “Dead Turquoise”, it turns dark green to spinach green and tarnishes somewhat, but that doesn’t detract from its charm for stone lovers.