Turquoise is an opaque, bluish green mineral, a hydrated copper & aluminium phosphate, with a high aluminium content. The natural gemstone is rare and has been prized as an ornamental gemstone for thousands of years because of its unique hue. It is considered to bring peace of mind, relieve stress and promote self-confidence. In Persia, at the time of Alexander the Great, turquoise was used on engagement rings, since according to the tradition, it signified trustworthy relationships.