Turquoise is a form of copper aluminium phosphate ranging in colour from blue to yellowish green. It is the most valuable of the opaque stones with intense blue being the most prized colour.
Turquoise is a symbol of courage and success. It was believed to protect from poison and to change colour as a warning of impending death. Buddha is said to have destroyed a monster using turquoise.
Turquoise can be easily scratched and is porous and, so, should not be brought into contact oil or dirty or soapy water.