Peridot Jewelry and Gemstone Information

To my mind, peridot is an under appreciated gemstone. Perhaps this has become the case due to the public's familiarity with low quality, olivey material which is inadequately cut and polished. Admittedly it can look pretty awful, but the lime and apple green stones given custom cuts and polishes are something else again.

DataValue
NamePeridot
VarietiesFayalite, Forsterite
CrystallographyOrthorhombic
Refractive Index1.635 - 1.673
Hardness (?)7
Specific Gravity (?)3.3 - 3.4
CleavageImperfect
Heat SensitivityNo
Wearability (?)* Very Good
EnhancementsNone
Special Care InstructionsNone
FormulaMg2SiO4-Fe2SiO4

Peridot August’s Birthstone

To my mind, peridot is an under appreciated gemstone. Perhaps this has become the case due to the public’s familiarity with low quality, olivey material which is inadequately cut and polished. Admittedly it can look pretty awful, but the lime and apple green stones given custom cuts and polishes are something else again.

Peridot belongs to the forsterite-fayalite mineral series which is part of the olivine group. It is one of the “idiochromatic” gems, meaning its color comes from the basic chemical composition of the mineral itself, not from minor impurities, and therefore will only be found in shades of green. Historically important sources in Egypt have been superceded by today’s main sources in Arizona and Pakistan. The high birefringence of this gemstone necessitates careful orientation in cutting to prevent “fuzziness” of reflections through the table. A distinctive, disk-like liquid and gas “lily pad” inclusion can often be seen under magnification.

Value

The vast majority of peridot rough produces sub-carat sized stones which in commercial quality are quite inexpensive. Both Sinkakas and Federman agree that stones in the 1- 4 carat range, or those with custom cuts, may command $40/ct. or more, while those over 4 carats increase exponentially in value to $100-150/ ct in largest sizes.

Source/Attribution: Barbara Smigel at Artistic Colored Stones.

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