What Is Peridot?Peridot is the gem variety of the mineral Olivine. It is also known as chrysolite.
In its rough unworked form, olivine is a dark oily green. Peridot varies in colour from yellow through limey green to brownish green.
It's chemical structure is magnesium iron silicate. The level of iron in the gem dictates how brown it is. The most prized peridots are rich deep green colour.
Uncut peridots - cabochons - are opaque and cloudy whereas the faceted stones are clear and brilliant. More on this below.
What To Expect From a Genuine Peridot.The first thing to notice is the peridot's size.
If what you are looking at is large i.e. more than 2cms on one side, then it is quite a rare gemstone. Most faceted peridots are small stones i.e. well under 2cms.
Check the clarity of the peridot.
If your peridot is completely eye clean, with no visible inclusions then the price tag should be eye watering.
Many peridots have visible inclusions. These are fascinating to the gemmologist and also revealing about the provenance of the particular gemstone. Alien minerals inside the host can pinpoint the area a particular gemstone was mined or the temperatures from which the rocks cooled. Synthetic gemstones are usually flawless and lack this personality. Many peridots contain inclusions that look like water lily leaves. Occasionally you will see tiny bubbles in a synthetic gem.
And now for the brilliance.
Peridot has a wonderful oily lustre. When faceted it is strongly doubly refractive. This means that when you look into the peridot, the faceted edges will appear doubled.
Other Peridot FactsPeridot is the birthstone for August
Peridot can be found in Egypt, Myanmar, Norway, Arizona, Canary Islands, Australia and South Africa.
Rare and priceless large peridots of more than 200 carats can be seen adorning the shrine of the three magi in Cologne Cathedral.