They can be as large as pigeon eggs. Pearls can be found in the Persian Gulf, off the southern coast of India, the northern coast of Australia, and the coast of Central America. Rubies can be found in Upper Burma, Thailand, Sri Lanka, and Tanzania. Peridot or Chrysolite is the term used by the trade for the gem variety of olivine. In minerology, both names refer to olivine.
Peridot is yellow green, olive green, or grennish brown in color.
Peridot can be found in basic igneous rocks, in serpentinite and as a derived mineral in sands. They occur in plutonic rocks, plutonic pegmatites and carbonate rocks as embedded tabular, short columnar, or barrel-shaped crystals. Opal belongs to the quartz group. A special characteristic of precious opal is its rainbow-like iridescence which changes with the the angle of observation. Precious opals with light or base colors are are white opals.