Turquoise is a blue-green gemstone and the color associated with it. It’s a mineral, specifically a hydrous phosphate of copper and aluminum, with the chemical formula CuAl6(PO4)4(OH)8·4H2O. Historically, it’s been highly valued as a gem and ornamental stone in various cultures for thousands of years. 

Here’s a more detailed look at turquoise:
As a Gemstone:Value: Turquoise is considered rare and valuable, especially in its finer grades. 
Uses:
It’s used in jewelry, often cut as cabochons (smooth, rounded stones). It’s also carved, used in inlays, and fashioned into beads for necklaces. 

History:
Turquoise has a rich history, with evidence of its use found in ancient Egypt, Persia, and among Native American tribes. It was often considered a protective talisman or a symbol of good fortune.