Where is Ruby found?
Corundum (Al2O3) with Chromium impurities
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Open the appRuby occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Ruby
Mogok Valley, Myanmar (Burma)
Historically the most important source of high-quality 'pigeon's blood' rubies, found in marble-hosted deposits and associated alluvial placers.
Mong Hsu, Myanmar
A significant source discovered in the 1990s, producing rubies often requiring heat treatment to improve color.
Mozambique
Currently a major global source, particularly from the Montepuez deposit, producing a wide range of ruby qualities.
Thailand (Chanthaburi, Trat)
Known for dark red to brownish-red rubies, often found in basaltic host rocks and alluvial deposits.
Sri Lanka (Ratnapura)
Produces rubies of various shades, often lighter red or pinkish, from alluvial deposits.
Tanzania (Winza, Longido)
Winza is known for vibrant, untreated rubies. Longido produces rubies in zoisite matrix.
Vietnam (Luc Yen, Quy Chau)
Produces fine quality rubies, often from marble-hosted deposits.
Madagascar
Various deposits producing rubies of different qualities and colors.
Collecting tips
- Look for associated minerals. In marble-hosted deposits, rubies may be found with calcite, phlogopite, spinel, and graphite. In basalt-hosted deposits, they can be associated with feldspar, amphibole, and other mafic minerals. In alluvial deposits, look for heavy mineral concentrates.
- Check for hardness. Ruby is very hard (Mohs 9). It will scratch quartz (Mohs 7) and most other common minerals. This can help differentiate it from softer red minerals like garnet or spinel.
- Observe crystal habit. Look for hexagonal prisms, tabular crystals, or bipyramidal forms. While often found as water-worn pebbles in alluvial deposits, primary deposits may yield well-formed crystals.
- Examine color and transparency. Rubies exhibit a distinct red color. High-quality rubies are transparent to translucent. Opaque red corundum is not typically considered gem-quality ruby.
- Consider fluorescence. Many rubies, especially those from marble-hosted deposits, fluoresce red under long-wave UV light due to chromium content. This can be a helpful identification aid, though not all rubies fluoresce strongly.
Quick Check
- Color:
- Red (pinkish-red to deep red)
- Luster:
- Vitreous to adamantine
- Streak:
- White
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