Peridot (Mg,Fe)₂SiO₄, the gem-quality variety of the mineral olivine, is designated as the modern sixteenth wedding anniversary gemstone by Jewelers of America. Its vivid, unambiguously yellow-green colour — produced entirely by iron within the crystal structure, with no treatment capable of altering or enhancing it — has long carried associations with renewal, vitality, and growth, qualities that lend themselves naturally to the symbolism of a marriage entering its second decade and a half. Traditional gift lists for the sixteenth anniversary cite silver holloware, but the modern gemstone designation has largely supplanted this in contemporary jewellery practice.

Gemological Character

Peridot belongs to the orthorhombic crystal system and has a refractive index of approximately 1.654–1.690, with a birefringence of 0.036 that can produce a characteristic doubling of back facets visible under magnification. Its specific gravity falls between 3.27 and 3.37, and its hardness of 6.5 on the Mohs scale warrants some care in everyday wear — a consideration worth communicating when the stone is set in rings intended for regular use. The colour range runs from a pale yellowish green through the most prized pure grass-green to a deeper olive, with the finest material showing a saturated, almost luminous green free of brownish or yellowish modifiers.

Principal Sources

The most historically significant deposit is the island of Zabargad (St John's Island) in the Egyptian Red Sea, worked for at least two millennia and the probable source of many ancient stones once called topazios. Myanmar's Mogok Valley yields peridot of exceptional transparency, while the Sapat Gali locality in Pakistan's Kohistan district has, since the 1990s, produced some of the finest large crystals known, with vivid pure-green colour and remarkable clarity. The San Carlos Apache Reservation in Arizona is among the world's most productive sources by volume, supplying a significant proportion of commercial-grade material. Chinese deposits in Hebei province have also contributed to the market since the late twentieth century.

Treatment and Stability

Peridot is not routinely treated. No heat treatment, irradiation, or fracture-filling process is in standard commercial use for this species, making it one of the few coloured gemstones that reaches the consumer in an essentially natural state. Owners should nonetheless be aware that peridot is susceptible to acids and to prolonged exposure to perspiration, and that ultrasonic and steam cleaning are inadvisable; warm soapy water and a soft brush remain the recommended cleaning method.

In the Trade

Fine peridot from Pakistan commands a meaningful premium over commercial-grade Arizona material, with top stones of two carats and above in pure green showing the greatest price differentiation. The gem's complete absence of routine treatment is increasingly valued by buyers seeking transparency in the supply chain, and laboratory reports from organisations such as the GIA confirm species identification and, where relevant, geographic origin. As an anniversary gift, peridot occupies a relatively accessible price point compared with the ruby of the fortieth or the emerald of the fifty-fifth, making it a practical as well as symbolically apt choice for the sixteenth year.