What it is confused with
Ruby, garnet and synthetic spinel, which is common and often used to imitate other gems. Spinel is singly refractive, unlike ruby.
Red, pink, blue, purple, black
Spinel birthstone
Spinel, the birthstone for August, is magnesium aluminum oxide (MgAl₂O₄), red, pink, blue, purple, black, rated 8 on the Mohs scale. Traditionally, it is associated with renewal and recovering energy after depletion — attributed, not demonstrated.
- Mohs hardness
- 8 scratches window glass
- Crystal system
- Cubic MgAl₂O₄
- Main sources today
- Myanmar also Tanzania, Sri Lanka
Is Spinel a birthstone?
Yes. Spinel is the modern birthstone for August.
18 pages · printable
The 2027 Sky Calendar — free PDF
Every retrograde, eclipse, new and full moon of 2027 to the minute, already converted to your city. A month to a page, ready to print.
Properties
Composition
Magnesium aluminum oxide (MgAl₂O₄)
Hardness (Mohs)
8
Crystal system
Cubic
Color
Red, pink, blue, purple, black
Mined in
Myanmar, Tanzania, Sri Lanka, Vietnam, Tajikistan
Worth knowing
Several famous "rubies" in the British Crown Jewels — including the Black Prince's Ruby — are spinel.
History
Recognized as distinct from ruby only in 1783.
Buying
Buying Spinel: fakes, value and treatments
What decides the price
Vivid red, bright "hot pink" from Tanzania and cobalt blue are the most prized. Most spinel is untreated, which buyers appreciate.
Where it is used
Fine jewelry, and increasingly a durable alternative to ruby and sapphire.
A less familiar fact
The Black Prince's Ruby in the British Imperial State Crown is actually a red spinel; spinel became an August birthstone in 2016.
Practical
Caring for Spinel
How to clean it
Warm soapy water. Durable and safe in ultrasonic.
How to tell it is real
Historically confused with ruby, and several crown rubies turned out to be spinel. Spinel is singly refractive and ruby is not, which settles it under a loupe.
How hard is Spinel?
Spinel is hard, has no real cleavage and is seldom treated, which makes it one of the easiest stones here to wear every day and to clean. Only Topaz shares its place on our scale. Among the stones in this reference, the next softer is Aquamarine (7.5–8) and the next harder Alexandrite (8.5).
Spinel, at 8, is harder than 37 of the other 42 stones here and softer than 4.
Traditional associations
Spinel is traditionally associated with renewal and recovering energy after depletion. Chakra in crystal practice: Root, Heart. Element: Fire.
Questions about Spinel
What is Spinel made of?
Magnesium aluminum oxide (MgAl₂O₄), crystallizing in the cubic system.
Which month is Spinel the birthstone for?
August.
Where does Spinel come from?
Myanmar, Tanzania, Sri Lanka, Vietnam, Tajikistan.
Can Spinel be worn every day?
Yes, and it is easy to live with: at 8 on the Mohs scale, it is durable and even safe in an ultrasonic cleaner.
Cite this page
AstroHot. “Spinel Birthstone: The August Stone — Meaning and Properties.” Accessed October 28, 2026. https://astrohot.com/crystals/gemstones/spinel/
For Wikipedia
{{cite web |title=Spinel Birthstone: The August Stone — Meaning and Properties |url=https://astrohot.com/crystals/gemstones/spinel/ |website=AstroHot |access-date=2026-10-28}}