Precious Stones · rare
Ruby
Ruby is a red variety of corundum, the second hardest natural mineral. Its intense red color comes from chromium impurities.
Also known as: red corundum, july birthstone, precious gem.
Ruby properties at a glance
| Type | Precious Stones |
|---|---|
| Chemical formula | Al2O3 |
| Mohs hardness | 9 |
| Crystal system | trigonal |
| Luster | adamantine |
| Streak | White |
| Cleavage | None |
| Fracture | Conchoidal |
| Specific gravity | 4 |
| Transparency | transparent |
| Common colors | Red, Pinkish Red, Purplish Red |
| Rarity | rare |
Geology & background
Forms in metamorphic rocks when aluminum-rich minerals are subjected to heat and pressure with trace chromium.
Called the 'King of Gems' in ancient India, rubies have been treasured for over 2,000 years.
How to identify Ruby
- Check whether the specimen's color and texture match typical Ruby examples.
- Photograph a fresh surface in natural light and avoid shadows, glare, or wet surfaces.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Full Ruby identification guide: checklist, home tests and look-alikes →
Ruby vs similar stones
Not sure it isn't something else? Side-by-side comparisons with the stones most often confused with Ruby.
Where Ruby is found
Ruby is reported from multiple localities or geological settings. Exact locality should be verified from specimen provenance, maps, or field notes.
How much is Ruby worth?
| Entry-level specimen | $1000 |
|---|---|
| Typical collector specimen | $10000 |
| Premium specimen | $100000+ |
Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
Common uses
- Jewelry
- Watches
- Lasers
Interesting facts
- The most valuable rubies are 'pigeon blood' red from Myanmar
- Rubies and sapphires are the same mineral, just different colors
- Ancient warriors implanted rubies in their skin for protection
Care & safety
Treat Ruby as a collector specimen unless hardness, cleavage, and fracture are confirmed.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a properly rated respirator.
Ruby FAQ
What is Ruby?
Ruby is a red variety of corundum, the second hardest natural mineral. Its intense red color comes from chromium impurities.
How much is Ruby worth?
Entry-level Ruby specimens sell for around $1000, a typical collector specimen for about $10000, and premium pieces for $100000 or more. Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
How hard is Ruby?
Ruby has a Mohs hardness of 9. It scratches glass, steel and even quartz; only harder gems will mark it.
Where is Ruby found?
Notable sources of Ruby include Myanmar, Thailand, Sri Lanka, Madagascar, and Tanzania. Forms in metamorphic rocks when aluminum-rich minerals are subjected to heat and pressure with trace chromium..
What is Ruby used for?
Ruby is used for jewelry, watches, and lasers.
