August has three birthstones: peridot, spinel, and sardonyx. Peridot is a yellowish-green olivine; spinel comes in red, pink, blue, and other colors; and sardonyx is a banded red and white chalcedony, the oldest of the three.
Peridot is one of the few gems found in meteorites, in a type called pallasite, as well as in volcanic rock on Earth, according to the Gemological Institute of America (GIA).
Spinel was added to the August list only in June 2016, but it has been mistaken for ruby for centuries: the Black Prince’s “Ruby” in the British Imperial State Crown is a spinel. Sardonyx, the oldest August stone, was favored for Roman seals because “hot wax would not stick to it.”
Table of Contents
What are the August birthstones?
Peridot, spinel, and sardonyx are all August birthstones in GIA’s August guide; the British list gives peridot and sardonyx. The table compares the three.
| Property | Peridot | Spinel | Sardonyx |
|---|---|---|---|
| Mineral | Olivine (gem variety) | Spinel | Chalcedony (layers of sard and onyx) |
| Mohs hardness | 6.5–7 | 8 | 6.5–7 |
| Toughness | Fair to good | Good | Not listed |
| Colors | Yellowish green to greenish yellow | Red, pink, orange, purple, violet, blue, bluish green | Bands of brownish red, brown or dark orange with white or black |
| Main sources | China, Myanmar, Pakistan, Tanzania, Vietnam, United States (Arizona) | Tajikistan, Myanmar, Sri Lanka, Vietnam, Tanzania, Pakistan | India, Brazil, Germany, Madagascar, Uruguay, United States |
| Wedding anniversary | 16th | 22nd | Not listed |
| Added to the U.S. list | Original stone | June 2016 | Traditional |
| Zodiac signs for August birthdays | Leo (to about August 22) and Virgo (from about August 23) | Same | Same |
Why does August have three birthstones?
Sardonyx is the ancient August stone, peridot became the main modern stone, and spinel was added in 2016 by Jewelers of America and the American Gem Trade Association to offer more color choice.
Some summary lists show only peridot and spinel, but GIA’s August guide covers all three. The full comparison of months is in the Birthstones by Month chart.
August birthstone colors
The August birthstone color can be yellow-green (peridot), almost any color from red to blue (spinel), or banded reddish brown and white (sardonyx). The table shows the main options.
| Stone | Colors | Notable color sources |
|---|---|---|
| Peridot | Yellowish green to greenish yellow; the color comes from the mineral itself, so peridot occurs in green only | Arizona (San Carlos Apache Reservation), Pakistan, Myanmar |
| Spinel | Hot pink and red (Myanmar, Mogok); blue, pink and purple (Sri Lanka); pinkish and orangy red (Tanzania, found 2007) | Myanmar, Sri Lanka, Vietnam (Luc Yen, since the 1980s), Tanzania |
| Sardonyx | Brownish red to dark orange sard layered with white or black onyx | India, Brazil |
Peridot from space: an August birthstone from meteorites
Some peridot reaches Earth inside pallasite meteorites, stony-iron meteorites that contain olivine crystals. Most gem peridot, though, comes from volcanic rock on Earth, including the San Carlos Apache Reservation in Arizona and, historically, Egypt’s Zabargad Island, where mining began around 340–279 BCE. Peridot also occurs at Hawaii’s Peridot Beach, according to GIA.
Spinel vs. ruby: the August birthstone once mistaken for July’s
For centuries red spinel was confused with ruby, because both occur in the same deposits and look alike. The Black Prince’s “Ruby,” owned by a succession of Moorish and Spanish kings before reaching the English crown, is a red spinel. The two can be told apart by their mineral properties.
| Feature | Red spinel (August) | Ruby (July) |
|---|---|---|
| Mineral | Spinel | Corundum |
| Mohs hardness | 8 | 9 |
| Pleochroism (color change with viewing angle) | None | Present |
| Birthstone guide | This page | July Birthstone |
August birthstone meaning and history
Peridot’s name comes from the Arabic faridat, meaning gem; spinel’s from the Latin spina, meaning thorn. GIA records the following history:
| Stone | History |
|---|---|
| Peridot | The Shrine of the Three Holy Kings in Cologne Cathedral is decorated with 200 carats of gems once believed to be emeralds, which are in fact peridot |
| Peridot | Often confused with topaz and emerald in history; worn as a talisman against evil |
| Spinel | Long mistaken for ruby; used as a remedy for blood loss and “believed to ease anger and promote harmony” |
| Sardonyx | Possibly a stone in the High Priest’s breastplate in the Old Testament; popular for Roman seals and signet rings |
These beliefs are folklore; they describe tradition, not gemological properties.
Choosing and caring for an August birthstone
Spinel is the most durable August birthstone, at 8 on the Mohs scale with good toughness, and is suited to everyday rings; peridot and sardonyx need more care. GIA gives these care rules:
- Peridot: clean only with warm, soapy water and a soft brush; never use ultrasonic or steam cleaners. Rapid or uneven heat can fracture peridot, and sulfuric acid, hydrochloric acid and even acidic perspiration can attack it (GIA peridot care).
- Spinel: warm soapy water is always safe; ultrasonic and steam cleaning are generally safe unless the stone is fractured or fracture-filled. High heat can fade some spinel colors (GIA spinel care).
- Sardonyx: use warm soapy water and a soft brush; use ultrasonic and steam cleaners with caution. Sardonyx is commonly dyed, and high heat can affect its color.
Peridot’s green is sometimes compared with emerald, the May birthstone, but peridot is a yellower green and a different mineral.
What the August birthstone is not
The August birthstones are often misunderstood. The points below separate the facts.
- August does not have only one birthstone. Peridot, spinel and sardonyx are all August stones.
- Peridot is not emerald. Cologne Cathedral’s “emeralds” turned out to be peridot.
- Red spinel is not ruby. It is a different mineral, though the two were confused for centuries.
- Sardonyx is not onyx alone. It combines layers of reddish sard and white or black onyx.
Frequently asked questions
What color is the August birthstone?
The main August birthstone, peridot, is yellowish green. Spinel, the second August stone, comes in red, pink, orange, purple and blue, and sardonyx is banded reddish brown and white.
What is the most durable August birthstone?
Spinel is the most durable August birthstone, at 8 on the Mohs scale with good toughness, which makes it suitable for everyday rings.
When was spinel added as an August birthstone?
Spinel was added as an August birthstone in June 2016 by Jewelers of America and the American Gem Trade Association.
