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, pronounced “per-i-doh, -dot”, is a gem-quality variety of the mineral olivine. The name “peridot” comes from the Arabic word “faridat”, meaning gem. Sometimes referred to as “chrysolite” or “the poor man’s emerald”, peridot is one of the oldest gemstones, with records tracing back to 1500 BC.
Unlike most gemstones formed in the earth’s crust, peridots are formed in the earth’s mantle region. Peridot crystals form in the earth’s magma and get erupted to the surface by a tectonic or volcanic activity, where they are found in igneous rocks. Interestingly peridot has also been found in fallen meteorites and comet dust.
Peridot is an idiochromatic gem. It means its colour comes from the initial chemical composition of the mineral (iron magnesium silicate) and not from impurities. This is the reason peridot comes only in green colour, although the shades of green vary from light yellowish to dark brownish-green, depending on the amount of iron the gem contains. In rare cases, there may be traces of nickel and chromium found.
The most important deposits of peridot are found in the Kashmir region (Pakistan) and the Pakistan-Afghanistan border region. Other deposits are found in Myanmar (Burma), Vietnam, China, Australia, Brazil, Kenya, Mexico, Norway, South Africa, Sri Lanka, Tanzania and the United States (Hawaii and Arizona).
Peridot is one of the unique gemstones that comes in a single colour – green. However, depending on the level of iron content, the depth of green may vary from light yellowish-green to olive and dark brownish-green.
Peridots are never too light or too dark. They always have a well-saturated colour. Its best colour peridot shows under natural daylight, but its vivid green colour does not change under artificial light too.
The most sought-after colour peridots have an iron content of less than 15% and typically include traces of nickel and chromium, which contribute to their vivid colour. Deep and intense green coloured peridots are considered the most valuable, while the yellowish-green variety is the most common shade.
Peridot Clarity and Cut
Peridots are transparent gemstones that usually come eye-clean, meaning they do not have visible inclusions. Larger specimens may appear slightly cloudy because of the presence of impurities.
When cut and polished, peridot has an attractive vitreous lustre. These gems are typically faceted due to their excellent transparency. Peridot can be found in many traditional shapes and cuts such as round, oval, emerald, cushion, etc.
Peridot Care and Cleaning
Peridot is a relatively hard and durable gemstone, 6.5 – 7 on the Mohs hardness scale. However, is it softer than many other gems, so care should be taken to prevent scratches.
Peridot is known to burst under stress, so it is recommended to avoid settings that can expose the gem to high pressure, for example, tension setting. Also, avoid extreme temperature changes, as they can harm the gem. Do not wear your peridot jewellery while playing sports, exercising, gardening or tidying up. Household cleaners usually contain hydrochloric or sulfuric acid, which can cause your gem to lose its shine. Put your peridot jewellery on last when dressing. Chemicals from makeup, hairspray, perfume and body creams can change the colour of the gemstone or make it look dull.
To clean peridots at home, you add some mild dishwashing soap liquid into warm water. Stir the water and dish soap together using a spoon or your finger. Carefully place your jewellery in the liquid you have prepared and soak it for about 20 – 30 minutes. After soaking, use a soft toothbrush to remove the dirt. Brush the peridot jewellery gently so as not to loosen the prongs, paying particular attention to all sides and edges. Make sure you clean the lower part of the gem as well. The base of the mounting underneath the stone is where a lot of dirt builds up. Next, rinse out your jewellery with clean water and dry it with a soft and lint-free cloth.
Do not use steam or ultrasonic cleaners to clean peridots as they are relatively fragile and do not tolerate rapid temperature changes. Such conditions may cause fractures and discolouration.
When storing peridots, keep them separated from other gems and jewellery. For better protection, wrap them with a soft cloth and place them inside a fabric-protected jewellery box to avoid scratches from other harder gemstones.
|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|
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