Peridot is one of the few gemstones that occur in only one color, an olive green. The intensity and tint of the green, however, depends on how much iron is contained in the crystal structure, so the color of individual peridot gems can vary from yellow- to olive- to brownish-green. The most valued color is a dark olive-green.

Peridot olivine is the birthstone for August.

Confusion with other gems

It is sometimes mistaken for emeralds and other green gems. In fact notable gemologist George Frederick Kunz discussed the confusion between emeralds and peridots in many church treasures, notably the "Three Magi" treasure in the Dom of Cologne, Germany.

Geologically

Olivine, of which peridot is a type, is a common mineral in mafic and ultramafic rocks, and it is often found in lavas and in peridotite xenoliths of the mantle, which lavas carry to the surface; but gem quality peridot only occurs in a fraction of these settings. Peridot can be also found in meteorites.

Abundance

Olivine in general is a very abundant mineral, but gem quality peridot is rather rare. This mineral is precious.

Locations of occurrence

Peridot olivine is mined in North Carolina, Arizona on the San Carlos Reservation, Hawaii, Nevada, and New Mexico, in the US; and in Australia, Brazil, China, Kenya, Mexico, Myanmar(Burma), Norway, Pakistan, Saudi Arabia, South Africa, Sri Lanka, and Tanzania.

 

For more information try these links:

http://www.gemstone.org/index.php?option=com_content&view=article&id=101:sapphire&catid=1:gem-by-gem&Itemid=14

http://minerals.usgs.gov/minerals/pubs/commodity/gemstones/sp14-95/peridot.html