Last updated on July 31, 2023
Peridot is one of the three birthstones of August, along with spinel and sardonyx. Known to the Egyptians as “the gem of the sun”, peridot is one of the few gemstones that comes in a single colour and is believed to cleanse the mind of negativity.
Peridot Origin and Formation
Peridot is a gem-quality variety of the mineral olivine. Its name is believed to have originated from the Arabic word “faridat,” meaning “gem” or “precious stone.” The Arabic word “faridat” was later adopted and adapted into the Old French term “peritot” and finally evolved into the modern name “peridot” that we use today.
Peridot forms under specific geological conditions, primarily in the earth’s mantle, which is the layer located between the earth’s crust and its core. The process of peridot formation begins deep within the mantle, where high pressure and high temperatures facilitate the creation of olivine crystals. When certain geological events, such as tectonic or volcanic activities, occur, the mantle rocks carrying the olivine crystals can be thrust upwards towards the earth’s surface. During this journey, these crystals undergo cooling and solidification, eventually turning into the gem-quality peridot we know.
Another intriguing way peridot is exposed on the earth’s surface is through meteorite impacts. Occasionally, peridot has been found in fallen meteorites and comet dust, adding an element of cosmic wonder to its origin story.
Peridot deposits can be found in various parts of the world. Some of the most significant deposits are located in regions like Kashmir and the border area between Pakistan and Afghanistan. Other notable deposits are located in countries like Myanmar (Burma), Vietnam, China, Australia, Brazil, Kenya, Mexico, Norway, South Africa, Sri Lanka, Tanzania, and the United States (specifically Hawaii and Arizona).
Peridot’s colour is one of its most captivating and distinctive features, setting it apart from many other gemstones. This enchanting gem is renowned for its vivid and alluring shades of green, ranging from a delicate, pale yellow-green to a rich, deep olive or dark brownish-green. Its colour palette is reminiscent of the lush landscapes and the vibrant hues found in nature.
The depth and intensity of a peridot’s green colour primarily depend on the amount of iron present in its chemical composition. Peridots with higher iron content tend to exhibit a deeper and more intense green hue, while those with lower iron content lean towards the lighter, more yellowish-green end of the spectrum.
What makes peridot truly exceptional is that it is one of the few gemstones considered idiochromatic, meaning its colour is derived from its intrinsic chemical composition rather than from impurities. In the case of peridot, its colouration results from the presence of iron in its crystal structure – iron magnesium silicate.
The most prized peridots have a vibrant, intense green colour that is evenly distributed throughout the gemstone, displaying excellent saturation and brilliance. These gems shine with a captivating glow, especially when viewed under natural daylight, which enhances their radiant green hue. Even under artificial lighting, peridot retains its vivid green colour, further highlighting its allure.
Peridot’s clarity is an essential aspect that contributes to its overall beauty and value as a gemstone. In general, peridots tend to have good to excellent clarity, often boasting high transparency and minimal inclusions. These gemstones are formed deep within the earth’s mantle, and their journey to the surface is facilitated through volcanic or tectonic activity. During this process, peridots may encounter various mineral interactions, creating internal features like tiny crystals, mineral inclusions, or small fractures.
However, compared to other gemstones, peridot’s inclusions are usually not as prominent or visible to the naked eye. This characteristic allows for a cleaner and more transparent appearance, which enhances the gem’s brilliance and lustre.
Gemstone cutters play a crucial role in enhancing the peridot’s clarity during the faceting process. Skilful cutting can minimize the appearance of any inclusions, as well as strategically position facets to optimize light reflection and refraction, resulting in a more dazzling and eye-catching gem.
Eye-clean peridots are highly sought after and command a premium in the market due to their exceptional clarity and brilliance. However, it’s important to note that some collectors and jewellery enthusiasts appreciate certain types of inclusions in peridots, as they can lend a unique character to the gem and provide clues about its natural origin and formation. These inclusions, such as “lily pads” or “butterfly wings,” are seen as interesting features rather than detractors of the gem’s beauty.
Peridot cut plays a crucial role in revealing the gemstone’s inherent beauty, maximizing its brilliance, and enhancing its overall appeal. The cut is the result of the skilled artistry of lapidaries, who carefully shape the rough peridot crystals into exquisite gems.
Gem cutters strive to achieve a balance between emphasizing the gem’s natural colour, clarity, and brilliance while minimizing any inclusions or blemishes. The most common cut for peridot is the faceted cut, in many traditional shapes such as round, oval and pear.
Well-cut peridot will exhibit even light distribution and an appealing play of colours throughout the gem, captivating the eye with its brilliance and lustre. The symmetry of the cut is also crucial, as it ensures the gem is well-proportioned and balanced, enhancing its visual appeal.
Peridot Carat Weight
Peridots come in a wide range of sizes, from small, delicate chips to substantial, eye-catching gems. Due to the abundance of smaller peridots, they are often more readily available and affordable than larger ones.
The average carat weight of peridots used in jewellery typically ranges from about 0.25 carats to 2 carats. Larger peridots, beyond 5 carats, are considered rare and are highly valued for their exceptional size and captivating colour.
It’s essential to consider that the size of a peridot does not solely determine its value. Other factors, such as colour, clarity, cut, and origin, also significantly influence its worth. An exquisite peridot with rich, intense green colour and excellent clarity can be more valuable than larger peridot with lesser quality characteristics.
Peridot Care and Cleaning
Peridot is a relatively durable gemstone with a hardness rating of 6.5 – 7 on the Mohs scale, but compared to some other gems, it is still susceptible to scratches. Thus, it requires some care and attention to maintain its beauty over time.
One of the peculiarities of peridot is its tendency to fracture under stress, making it essential to avoid settings that expose the gem to high pressure, such as tension settings. Extreme temperature changes should also be avoided, as they can harm the gem. To preserve its brilliance and charm, refrain from wearing peridot jewellery during sports, exercise, gardening, or household chores.
Peridot can lose its shine when exposed to household cleaners containing hydrochloric or sulfuric acid, so it’s crucial to keep it away from such chemicals. Additionally, be mindful of wearing peridot jewellery after applying makeup, hairspray, perfume, or body creams, as these substances can alter the gem’s colour or dull its appearance.
For cleaning peridots at home, create a gentle solution by adding mild dishwashing soap liquid to warm water. Immerse your jewellery in the liquid for 20 – 30 minutes and then use a soft toothbrush to gently remove dirt and debris, paying attention to all sides and edges, including the lower part of the gem where dirt tends to accumulate. Rinse the jewellery thoroughly with clean water and dry it with a soft, lint-free cloth.
Avoid using steam or ultrasonic cleaners, as peridots are relatively fragile and can be damaged by rapid temperature changes, leading to fractures and discolouration.
When storing peridots, keep them separated from other gemstones and jewellery to prevent scratches. Wrap them in a soft cloth and place them inside a fabric-protected jewellery box for added protection.
|Chemical Name||Magnesium iron silicate|
|Colours||Pale green to brownish-green|
|Hardness||6.5 - 7 on the Mohs scale|
|Refractive Index||1.64 - 1.69|
|Specific Gravity||3.32 ~ 3.37|
|Birefringence||0.036 - 0.038|
|Lustre||Vitreous to greasy|
|Streak||White to greenish|
Featured image: photo33mm / Shutterstock