A lovely stone, Turquoise is one of the most recognized semiprecious gemstones in existence. It is considerably softer than Quartz and therefore is usually treated in some way for stability.It occurs naturally in shades ranging from sky blue to grey-green. The color variations are caused by the quantities of copper, iron or chromium in the soil. Different colors come from different regions and states. Turquoise is a beautiful and wonderful stone to work with and here are a few of my favorite pieces.