August has three gemstones – peridot, spinel and sardonyx. I am going to talk about peridot, that lovely green gemstone. Peridot only comes in the colour green, although the green can range from a pale green through to a brownish green. It has a hardness of 6.5 to 7 on Mohs’ scale so is suitable for most jewellery but can be brittle and so care is needed for rings and bracelets. Peridot does not appear to be the subject of much enhancement or treatments, unlike many other gemstones.
Prior to the early 18th century, peridot gemstones were called topaz but when the topaz family was actually identified gemmologically, a new name for the green gemstone was required. In 1790, the name ‘olivine’ was selected. The word ‘peridot’ is French for olivine and eventually, it was the French name that became commonly used, rather than olivine.
Pliny wrote about the beautiful green topaz stone being mined on the Red Sea island known by the Greeks and Romans as ‘Topazios’. It is the Island of Zabargad, now known as St John’s Island. Today, peridot is mined in Myanmar and Pakistan as well as a number of other sites, including China, Vietnam and the US. Peridot is formed in magma and is pushed to the surface through volcanic activity. Non-gem quality peridots are being found now on the surface in Hawaii as a result of the recent activity of the Kīlauea volano, having been formed in older lava flows.
One of the things I like about the peridot is how well it goes with other coloured gemstones. It looks lovely contrasted with amethysts and garnets in particular, as seen in the brooch above and in the ring below.