August Birthstone Guide: Peridot, Spinel & Sardonyx

If you or someone you love has an August birthday, you have options: August is one of the months with more than one birthstone — peridot, spinel, and sardonyx. Peridot is the vivid lime-green stone most people picture first, spinel is a gem so brilliant it was mistaken for ruby in crown jewels for centuries, and sardonyx is a banded stone treasured since the ancient world. Together they give August a range that runs from bright and summery to deep and historic.

This guide walks through why August has three birthstones, the meaning and lore behind each, the practical knowledge you’ll need to evaluate them, and how to think about August birthstone jewelry as both an everyday piece and a long-term family heirloom.

Why August Has Three Birthstones

The modern birthstone list was standardized by the American National Retail Jewelers Association — now Jewelers of America — in 1912, and peridot has long been August’s primary stone. Sardonyx is the older traditional August birthstone, prized for millennia before peridot took the lead. Spinel was added in 2016, when Jewelers of America and the American Gem Trade Association officially named it an additional August birthstone — a long-overdue recognition for a gem that had spent centuries disguised as ruby.

Each carries its own deep history. Peridot has been mined for over 3,500 years, famously from the volcanic island of Zabargad in the Red Sea, and some historians believe several of Cleopatra’s celebrated “emeralds” were actually peridot. Spinel sat in royal treasuries for centuries under the wrong name — the “Black Prince’s Ruby” in the British Imperial State Crown and the “Timur Ruby” are both actually spinels. Sardonyx, a banded blend of sard and onyx, was used by the Romans for seal rings and carved cameos, and by ancient warriors who believed it brought courage.

Peridot is also the traditional gemstone for the 16th wedding anniversary, giving August’s stones milestone meaning beyond a birthday.

The Meaning and Symbolism of August’s Birthstones

Each of August’s three stones carries its own symbolism:

• Peridot — light, positivity, and renewal. Called the “gem of the sun” by the ancient Egyptians, peridot has long been associated with warmth, good fortune, and protection from negativity.
• Spinel — vitality and revitalization. Traditionally believed to soothe away sadness and restore energy, spinel is a stone of encouragement and renewed passion.
• Sardonyx — courage, strength, and protection. Worn by Roman soldiers for bravery and long considered a stone of stability, sardonyx symbolizes resilience and steadfastness.

Together they make August rich for anyone who likes meaning in their jewelry: the sunny optimism of peridot, the fiery vitality of spinel, and the grounded strength of sardonyx.

How to Actually Evaluate August’s Birthstones

Because August’s three stones are so different, there is no single framework that applies to all of them. Each is judged on its own terms.

Peridot

Peridot is unusual among gems in that it comes in only one color — green — and is one of the few gemstones that is “idiochromatic,” meaning its color comes from the stone itself rather than trace impurities. It rates 6.5 to 7 on the Mohs scale, suitable for most jewelry with reasonable care. What matters most:

• Color — the single biggest value driver. The most prized peridot is a pure grass-green to slightly yellowish-green with no brown or olive tint. The finest color usually appears in stones above 10 carats.
• Clarity — the best peridot is eye-clean. Some stones show characteristic “lily pad” inclusions under magnification, which don’t necessarily reduce value if the stone is clean to the eye.
• Cut — peridot’s strong double refraction can create a slightly “doubled” look at facet edges, so skilled cutting matters.
• Origin — fine material comes from Pakistan (Kashmir region), Myanmar, and the San Carlos Reservation in Arizona, among others.

Spinel

Spinel is the connoisseur’s gem — brilliant, durable, and almost always natural and untreated, which is rare in the colored-stone world. It rates 8 on the Mohs scale, excellent for everyday wear. What matters:

• Color — spinel comes in a wide range: vivid red (the most valuable, rivaling ruby), hot pink, cobalt blue, lavender, and more. Saturated, vivid colors command the highest prices.
• Clarity — fine spinel is typically eye-clean, and because it’s so rarely treated, clean natural stones are highly prized.
• Cut and carat — well-cut stones that maximize brilliance are ideal; fine red and blue spinel above a few carats is genuinely rare.
• No treatment — one of spinel’s greatest selling points is that it is almost never heated or treated, so what you see is natural. Always confirm, but expect “no treatment” on most fine spinel.

Sardonyx

Sardonyx is a banded variety of chalcedony — layers of reddish-brown sard alternating with white or black onyx. It rates 6.5 to 7 on the Mohs scale and is valued more for pattern than for brilliance. What to look for:

• Banding — strong, well-defined contrast between the colored and white layers is most prized, especially for cameos and intaglios where the layers are carved.
• Color — rich, warm sard tones (reddish-brown to near-red) with clean white banding are classic.
• Polish and carving — because sardonyx is often carved, quality of workmanship matters as much as the raw material.

Alternative August Birthstones

Between peridot, spinel, and sardonyx, August already offers a lot of range, but a few related options are worth knowing:

• Green tourmaline or chrome diopside — for those drawn to peridot’s green who want a deeper or more saturated tone.
• Lab-grown spinel — widely available and inexpensive, long used in class rings and costume pieces; a durable, colorful option, though natural spinel is far more prized by collectors.
• Onyx or agate — for those drawn to sardonyx’s banded look, related chalcedonies offer similar carving-friendly character in other color combinations.

Each has a different character. For a durable everyday stone, natural spinel or peridot are the standouts; sardonyx suits those who love antique-style carved pieces.

Choosing an August Birthstone in Hawaii — and Peridot’s Island Connection

Peridot has a special resonance in Hawaii. It forms deep in the earth and is carried up by volcanic activity, and Hawaii’s volcanoes have produced tiny peridot grains for generations — the green-tinged sand at Papakōlea (Green Sand Beach) on the Big Island gets its color from olivine, the mineral peridot comes from. Hawaiian tradition has long linked these green grains to Pele, the volcano goddess, sometimes calling them “Pele’s tears.”

A quick, honest note for buyers: the olivine in Hawaiian sand is not gem-quality — it’s too small and included to cut into faceted stones — so fine peridot jewelry is sourced from larger crystals mined elsewhere. But the island connection makes peridot an especially meaningful birthstone for anyone with Hawaii ties.

At Jewel Box Hawaii, we work with vetted suppliers and disclose the nature and treatment of every stone. We encourage clients to view August’s stones in person — peridot’s exact green and spinel’s brilliance both read differently in person than in a catalog photo.

Caring for Peridot, Spinel & Sardonyx — Especially in the Islands

August’s stones range from moderately durable to tough, and Hawaii’s sunscreen, salt water, and sand are hard on any jewelry:

• Peridot needs some care. At 6.5–7 on the Mohs scale it can scratch and is sensitive to sudden temperature changes and acids — avoid ultrasonic cleaners and harsh chemicals. Clean with warm water, mild soap, and a soft cloth.
• Spinel is the easy one. At Mohs 8 and almost always untreated, it tolerates normal cleaning with warm soapy water and stands up well to daily wear, including rings.
• Sardonyx is porous — keep it away from chemicals. Like other chalcedonies it can absorb liquids and should be kept away from cosmetics, perfume, and cleaners. Wipe with a soft damp cloth.
• Take stones off before the ocean and pool. Salt water, chlorine, and impact against rock are hard on peridot and sardonyx especially.
• Rinse off sunscreen and oils that build up and dull any stone.

Cleaning, resetting, and general maintenance are part of our restoration and heirloom care services — particularly useful for softer stones like peridot and sardonyx that have been in the family for years.

Gift Ideas for an August Birthday

If you’re shopping for someone with an August birthday, a few directions worth considering:

• Peridot studs or a pendant — the bright, summery green is cheerful and wearable, and pieces that face less impact than rings suit peridot’s moderate hardness.
• A custom-designed piece featuring spinel or peridot — natural spinel in red, pink, or blue makes a rare, brilliant center stone. We routinely design around a single special stone.
• Spinel for a collector — for someone who appreciates gems, a fine natural untreated spinel is a connoisseur’s choice with a great backstory.
• An Aloha Pauahi heirloom bracelet with a peridot accent — for someone with deep Hawaiian roots, the Aloha Pauahi line celebrates cultural heritage alongside the personal milestone of an August birthday, and peridot’s island connection makes it especially fitting.

Schedule a Consultation

Whether you’re choosing a peridot for its island connection, hunting for a fine natural spinel, or designing a piece around an August birthday, we’d be glad to help. Browse our gemstone inventory or schedule a consultation to start a conversation.