Ruby is the red, gem-quality variety of corundum, colored primarily by trace amounts of chromium. It is highly valued for its intense color, extreme hardness, and lack of cleavage, making it a premier gemstone for jewelry collectors.
Is this ruby?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch ruby with a known reference. Ruby sits at Mohs 9 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ruby leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ruby typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: red.
- 5Look at form & habitCrystal system: trigonal. Typical habit: tabular hexagonal prisms.
Often confused with
Ruby vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ruby
Minerals reported to co-occur with ruby. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂O₃
- Mohs hardness
- 9
- Density
- 4.0 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Tabular Hexagonal Prisms
- Cleavage
- None
- Fluorescence
- Bright Red Under UV
- Rarity
- Rare
- Uses
- Gemstone, Collector
- Host rock
- Marble, Basalt, And Secondary Alluvial Deposits
- Typical price
- $50-5,000+ per carat depending on quality and size
Where rockhounds find ruby
20 mapped spotsClassic worldwide localities
- Mogok, Myanmar
- Jagdalek, Afghanistan
- Ratnapura, Sri Lanka
- Montepuez, Mozambique
U.S. states with ruby
Each link opens a state-specific list of mapped rockhounding spots that produce ruby.
Field-hunting tip
Look in marble, basalt, and secondary alluvial deposits country — that is the host setting where ruby typically forms. If you start seeing calcite, phlogopite, spinel in float, you are in the right ground. Field specimens usually show a tabular hexagonal prisms habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in North Carolina, Georgia, Montana — start trip planning there.
More ruby photos
Common questions
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Find ruby on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
