Ruby is the birthstone for July. Ruby is the red variety of the mineral corundum, colored by the element chromium. All other colors of gem-quality corundum are called sapphire, which means color is key for this royal stone.
Accordingly, the name “ruby” comes from rubeus, the Latin word for red. In ancient Sanskrit, ruby translated to ratnaraj, which meant “king of precious stones.” These fiery gems have been treasured throughout history for their vitality.
The chromium that gives ruby its red color also causes fluorescence, which makes rubies glow like a fire from within. Paradoxically, chromium is also what makes this gem scarce because it can cause cracks and fissures. Few rubies actually grow large enough to crystallize into fine quality gems, and these can bring even higher prices than diamonds.
Burma’s Mogok Valley historically produced the finest ruby material, famous for its deep blood-red color with purplish hues. These Burmese Rubies, also called Pigeon’s Blood Rubies, command a premium over brownish or orange-tinged varieties from other regions (source: American Gem Society).
To read an article on Rubies from the Gemological Institute of America (GIA) click: here