Peridot

Peridot Gemstones

• Hardness

  6.5 - 7.0.
  
  

• Occurrence

  St. John's Island, Zebirget Island, Red Sea (Egypt), Norway, Eifel, Germany, San Carlos (Arizona), Hawaii, Myanmar (Burma), and Italy.
  
  

• Appearance

  Olive green to yellowish green. The darker green is known as peridot, the yellower type chrysolite. Peridot and sardonyx are the birthstones of the month of August.
  

• Enhancements

  Peridot is rarely treated with colorless oil, wax, natural and synthetic unhardened resins into voids to improve appearance. Surface fractures are rarely filled with a colorless hardened substance.
  More information on gemstone enhancements.

Peridot

Peridot  is gem-quality olivine. Olivine is a silicate mineral with formula of (Mg, Fe)2SiO4. As peridot is the magnesium-rich variety (forsterite) the formula approaches Mg2SiO4.

Etymology

The origin of the name peridot is uncertain. The Oxford English Dictionary suggests an alteration of Anglo–Norman pedoretés (classical Latin pæderot-), a kind of opal, rather than the Arabic word faridat, meaning "gem".

The Middle English Dictionary's entry on peridot includes several variations : peridod, peritot, pelidod and pilidod – other variants substitute y for the i's seen here.

The earliest use in England is in the register of the St Albans Abbey, in Latin, and its translation in 1705 is possibly the first use of "peridot" in English. It records that on his death in 1245 Bishop John bequeathed various items to the Abbey: "He gave also three noble Rings, in one whereof is an Oriental Sapphire, of wonderful bigness: In another is the Stone call'd Peridot, in the middle whereof is set a Sapphire of great beauty; it is said to be good against the Cramp, and is made almost in the form of a Buckler: in the third Ring is also an Oriental Sapphire, but less than the former."

Appearance

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.

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.

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

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

In meteorites

Peridot crystals have been collected from some Pallasite meteorites. A famous Pallasite was offered for auction in April 2008 with a requested price of close to $3 million at Bonhams, but remained unsold.

Gemology

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.

The largest cut peridot olivine is a 310 carat (62 g) specimen in the Smithsonian Museum in Washington, D.C.

Peridot olivine is the birthstone for the month of August.