August birthstone: peridot, spinel and sardonyx, the guide

Three stones for a single month

August, like June, has several birthstones. The 1912 American list retained sardonyx and peridot. The British list gives peridot first. Finally, in 2016, the American jewellers' associations added spinel. The older list, for its part, offered sardonyx, carnelian, moonstone and topaz.

Having several stones means you have freedom of choice: pick the one you like.

Peridot: the olive green

Peridot is the gem variety of olivine, a magnesium iron silicate. Its colour, from yellow-green to olive, comes from the iron present in the stone itself: peridot almost never occurs in any other colour. Its hardness is 6.5 to 7. It is found in certain volcanic rocks, in Pakistan, China, Myanmar, the United States (Arizona), and even in meteorites (pallasites).

As far back as antiquity, it is said to have been mined on Zabargad (or St. John's Island), an island in the Red Sea. It is thought that the stone the Greek Bible calls “topaz” was in fact peridot: the words of the ancients do not always match ours. This is a view held by specialists, not a certainty.

Spinel and sardonyx

Spinel. It is a magnesium aluminium oxide with a hardness of 8, which occurs in red, pink, orange, blue, violet and black. It forms in the same regions as ruby (Myanmar, Sri Lanka, Tajikistan), and was for a long time mistaken for it. It remained little known to the public until it was added to the August list in 2016.

Sardonyx. Sardonyx is a banded chalcedony: bands of brownish red (sard) alternate with white (onyx). The Romans made cameos and seals from it, because the difference in colour between the bands makes it possible to carve a light relief against a dark background. Its hardness is 6.5 to 7.

Traditional symbolism

Peridot is associated with sunlight, cheerfulness and abundance in many cultures; it is often linked to the heart chakra. Sardonyx evokes calm strength and protection in the Roman tradition. Spinel, a more recent birthstone, has no tradition of its own: it is associated with vitality through its red colour, inherited from ruby.

These associations are symbols of tradition or of language, which vary between authors, with no scientific proof.

A little history: a list that evolves

The addition of spinel in 2016 is a good example of how these lists evolve. That year, the American jewellers' association and the American coloured gemstone trade association decided to add it as a third August stone, as an alternative to peridot and sardonyx. The reasons given relate to the stone's beauty and its greater presence on the market; some also see it as an effort to diversify the offer.

Other recent changes have taken place outside the United States: in 2021, Japanese jewellery associations added ten stones to their own list, the first such change in sixty-three years according to the press. These lists are therefore trade conventions, revised from time to time.

Other possible stones in August

• the carnelian, orange, from the older list;
• the moonstone, from the older list;
• the topaz, also on the older August list;
• the onyx, dark, a close relative of sardonyx;
• the green aventurine, for an affordable green.

Giving an August birthstone

Peridot is bright and affordable: a pendant, a ring (worn with care) or earrings. Spinel makes a simple and durable piece of jewellery. Sardonyx and carnelian suit signet rings and beads. For a modest budget, a small tumbled stone or a raw crystal is enough.

Browse our jewellery and gift ideas collections.

Care, treatments and imitations

Peridot. It scratches fairly easily and is sensitive to acids, knocks and temperature changes. Clean it with lukewarm water and mild soap, and dry it with a soft cloth; avoid ultrasonic cleaners and steam. Remove the ring for manual work. Peridot is generally untreated, which is an advantage.

Spinel. Sturdy: lukewarm water, mild soap, cloth. Synthetic spinels exist, sometimes sold as natural stones or used to imitate other stones (aquamarine, sapphire).

Sardonyx. Lukewarm water and a cloth; avoid harsh products. Its colours may be dyed, a common practice on chalcedonies; an onyx of perfectly uniform black is almost always dyed. Ask the seller.

Imitations. Green glass is the usual imitation of peridot; a very “clean” green stone at a low price deserves questions. See our guide to choosing and caring for your stones.

Frequently asked questions

Also read

The meanings mentioned belong to tradition and symbolism. They are neither promises of results nor medical advice. Back to Guide to birthstones.