Opal is a gemstone known for its colorful, scattered patterns that differ on each side. It is mainly found in Australia, which supplies 95% of the world's opal demand. Opals are divided into precious and common varieties, with precious opals displaying vibrant color play and common opals showing single-tone patterns. The rarest type is black opal, followed by white opal, both known for their strong color variations. Opals are used in various jewelry and can be cut thin or coated to protect their softer surfaces while still showing their attractive colors.