August Birthstones: Peridot, Spinel & Sardonyx Guide
August is a lucky month with three birthstones. Here's what peridot, spinel, and sardonyx each mean, why August has three, how they differ, and how to choose.
August is one of the fortunate months blessed with three birthstones — and they span the whole sweep of gem history. There's peridot, the sunny green gem born of volcanoes and even meteorites; spinel, the durable color-chameleon once mistaken for ruby in crown jewels; and sardonyx, the banded stone the ancients carved into cameos. Here's what each means and how to choose.
August Birthstones at a Glance
- Peridot: vivid yellow-green — the modern favorite.
- Spinel: durable, comes in every color; added in 2016.
- Sardonyx: banded red-brown & white — the ancient stone.
- Most durable: spinel (Mohs 8).
- Fun fact: peridot is found in meteorites.
August's Three Birthstones
Peridot, spinel, and sardonyx.
According to the GIA, August's birthstones are peridot, spinel, and sardonyx. Peridot is the one most people picture — that fresh lime-green — while spinel brings durability and endless color, and sardonyx brings thousands of years of history. Explore the month's gems in our August birthstone collection.
Why Does August Have Three Birthstones?
Three stones from three different eras.
Each August birthstone entered the picture at a different time. Sardonyx is the ancient, traditional stone, used since antiquity. Peridot became the primary modern birthstone and the one most associated with August today. Spinel is the newest, added in 2016 by the Jewelers of America and the GIA to honor a beautiful, long-underappreciated gem. Several months have multiple birthstones — June, October, November, and December among them — and August is firmly one of them.
Peridot — The Gem Born of Fire
And, remarkably, found in the stars.
Peridot is the gem variety of the mineral olivine, and it's unusual in the gem world: its green is idiochromatic, meaning the color is intrinsic to the stone (from iron) rather than an added trace element, so peridot is always some shade of green — from lime to olive. It rates 6.5 to 7 on the Mohs scale.
Its origin story is extraordinary. Peridot forms deep in Earth's upper mantle and rides to the surface in volcanic magma — one of only two gems (with diamond) not formed in the crust. It has even been discovered in meteorites called pallasites, giving some peridot a genuinely cosmic origin. Ancient Egyptians mined it on a Red Sea island as early as 300 BCE and prized it to drive away nightmares and evil; today the finest comes from Arizona, Pakistan, and Myanmar. Explore our peridot jewelry.
Peridot Jewelry
Handcrafted, made-to-order peridot rings and necklaces — a fresh, sunny gift for any August birthday.
Shop Peridot RingsSpinel — The Great Impostor
The gem history mistook for ruby.
Spinel is one of the most underrated gems in the world — and one of the most historically dramatic. For centuries, magnificent red spinels were mistaken for rubies: the famous "Black Prince's Ruby" and "Timur Ruby" in the British Crown Jewels are actually spinels. It comes in a rainbow of colors — red, pink, blue, purple, and black — and at Mohs 8 it's genuinely durable, making it excellent for everyday rings. Its long overlooked beauty is exactly why it earned a place as an official August birthstone in 2016.
Sardonyx — The Ancient Stone
August's oldest birthstone.
Sardonyx is a banded variety of chalcedony (a form of quartz), combining reddish-brown sard with white onyx layers to create striking parallel bands. It's the oldest of August's stones: the Romans carved it into cameos and signet rings, and soldiers wore it for courage and protection in battle. At about Mohs 6.5 to 7, it's a warm, earthy, history-rich alternative for August.
The Three August Birthstones Compared
At a glance.
| Stone | Look | Hardness | Character |
|---|---|---|---|
| Peridot | Lime to olive green | Mohs 6.5–7 | The modern favorite; cosmic origin |
| Spinel | Red, pink, blue, purple, black | Mohs 8 | Durable; once mistaken for ruby |
| Sardonyx | Banded red-brown & white | Mohs 6.5–7 | Ancient; carved into cameos |
Which August Birthstone Should You Choose?
Color, durability, or history.
- Choose peridot for the classic, cheerful August green and a gem with a one-of-a-kind volcanic-and-meteorite story.
- Choose spinel for the toughest, most colorful option — ideal for an everyday ring, and available in a red that rivals ruby.
- Choose sardonyx for warmth, history, and a beautifully different, earthy look.
August's "color" is usually taken as peridot green, though spinel and sardonyx broaden the palette considerably. Curious how August compares to other months? See our July birthstone guide and June birthstone guide.
Caring for August's Birthstones
Each has its own needs.
- Peridot — clean with mild soap and warm water and a soft brush; avoid ultrasonic cleaners, sudden temperature changes, and harsh chemicals; use a protective setting for rings.
- Spinel — the toughest of the three; warm soapy water is ideal, and it handles daily wear with ease.
- Sardonyx — wipe with a soft, damp cloth; keep away from harsh chemicals and prolonged sunlight, which can affect its color over time.
For more, see our ring care guide and how to clean jewelry at home.
August Birthstone FAQ
What are August's birthstones?
Why does August have three birthstones?
What is the main birthstone for August?
Is peridot really formed in space?
Which August birthstone is most durable?
What does peridot symbolize?
Celebrate an August birthday
From sunny peridot to durable spinel, every Aquamarise August birthstone piece is handcrafted and made to order, just for you.
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