Peridot Gems
Peridot is the green gem variety of olivine, a magnesium-iron silicate that forms deep in the Earth and reaches the surface through volcanic or tectonic activity. It is known for bright yellowish green to olive-green colors and is the traditional birthstone for August. For detailed buying factors, see our peridot gemstone properties and value guide.
What Is Peridot?
Peridot is gem-quality olivine. In gem use, the name applies to transparent to translucent green stones with enough beauty and durability for jewelry. Unlike many gem materials that occur in several distinct colors, peridot is valued within a relatively narrow green range, from lively yellow-green to deeper olive or brownish green.
The older nickname “poor man’s emerald” is sometimes encountered, but it is not especially helpful for modern buyers. Peridot is not a substitute for emerald; it is a separate gemstone with its own chemistry, appearance and value factors.
Composition and Chemistry
Olivine is best understood as a mineral group or solid-solution series between two end members: forsterite, the magnesium-rich end member with the formula Mg2SiO4, and fayalite, the iron-rich end member with the formula Fe2SiO4. Because HTML subscript tags are not used in this article format, the general olivine formula is often written in plain text as (Mg,Fe)2SiO4.
Although iron is the main coloring element in peridot, gem-quality peridot is usually closer to forsterite than fayalite in composition. Fine green color is commonly associated with relatively low iron content, often less than 15%, and trace elements such as nickel and chromium may also influence the color.
How Peridot Forms
Most gem minerals form in the Earth’s crust, but peridot is notable because it commonly forms much deeper, in the upper mantle. Peridot crystals can form in magma from the upper mantle, roughly 20 to 55 miles below the surface, and are later brought upward by volcanic or tectonic processes. They are often found in extrusive igneous rocks.
This deep origin is one reason peridot is frequently compared with diamond in educational writing. Diamond also forms in the mantle, generally at greater depths and under more extreme temperature and pressure conditions. The comparison is useful for origin, but the two gems are very different in chemistry, appearance and physical properties.
Peridot Color and Appearance
Peridot’s color is controlled mainly by iron in its crystal structure. The most desirable stones are typically bright, clean green to yellowish green, while higher iron content can produce darker olive or brownish green tones. Brownish or overly dark stones are usually less desirable than lively green stones of good clarity.
Gem-quality peridot is rarer than the abundance of olivine as a rock-forming mineral might suggest. Buyers often look for a combination of attractive color, good transparency, precise cutting and minimal eye-visible inclusions.
Sources and Mining
Important peridot sources include Burma, now Myanmar, Pakistan, China, Vietnam and the United States. Mogok in Myanmar has traditionally been associated with fine peridot, and Pakistani peridot is also highly regarded in the gem trade.
The United States has been an important source, especially Arizona. Deposits on the San Carlos Apache Reservation, including the Peridot Mesa area east of Globe in Gila County, have long been significant for commercial production. Another Arizona locality associated with peridot is Buell Park in Apache County, north of Fort Defiance.
Source alone does not determine quality. Fine peridot may come from several localities, and individual stones should be judged by color, clarity, cut, size and overall appearance.
Notable Peridot Specimens and History
Large fine peridot gems are uncommon. Notable examples include a 310-carat cut peridot in the Smithsonian Institution in Washington, D.C.; a 192.75-carat stone associated with the Russian czars in the Diamond Treasury in Moscow; and a 146-carat peridot in the Geological Museum in London.
Peridot also has a long cultural history and has been valued for centuries for its distinctive green color. For a fuller historical account, see our article on the history and origins of peridot gems.
Value, Size and Treatments
Peridot is generally affordable in small commercial sizes, but prices can rise sharply for clean, well-cut stones over 5 carats. Stones in the 10 to 15 carat range are much rarer, especially when they show strong color and good clarity.
Peridot is not known for routine color or clarity enhancement in the way some other gemstones are. In normal trade practice, peridot is generally sold untreated, which is an important point for buyers who prefer natural-color gems. As with any gemstone purchase, disclosure from the seller and clear product information remain important.
Peridot Meaning and Birthstone Use
Peridot is the traditional birthstone for August and is often chosen for birthstone jewelry, anniversary gifts and custom designs. Some buyers are also interested in symbolic or folklore associations. These beliefs are cultural or traditional rather than scientific; for that topic, see our page on peridot meaning, healing powers and practical uses.
Buying Loose Peridot
When choosing loose peridot, prioritize color first, then clarity, cut quality and size. A bright, evenly saturated green stone with good transparency will usually be more appealing than a larger stone with a dull or brownish appearance. You can browse available loose peridot for sale in a range of shapes and sizes.
