The Ruby is named after its red color (Latin Rubeus). It wasn't until the 1800 that Ruby, as well as sapphire, was recognized as belonging to the corundum group. Before then red spinel and garnet were also designated as ruby. Ruby gets its tint from chrome, and iron for it's brown hues. The color differs in each deposit, so its impossible to determine any specific stone's source. The description "Burma-ruby" and "Siam-ruby" stand for quality not location. The most desirable color is "Pidgin's blood", pure red with a hint of blue. Color distribution is usually uneven, in stripes and/or spots. It makes a rough stone, uncut, but when cut, can approach the luster of that of a diamond.

• Color : Varying red
• Color of streak : White
• Mohs' hardness : 9
• Specific gravity : 3.97 - 4.05
• Cleavage : None
• Fracture : Small conchoidal, uneven, splintery, brittle
• Crystal system : Hexagonal (trigonal); hexagonal prisms or tablets, rhombohedrons
• Chemical composition : Al2O3, aluminum oxide
• Transparency : Opaque, translucent, transparent
• Refractive index : 1.766 - 1.774
• Double refraction : -0.008
• Dispersion : 0.018
• Pleochroism : Strong; yellow-red, deep ruby-red
• Absorption spectrum : 6942, 6928, 6680, 6592, 6100-5000, 4765, 4750, 4685
• Fluorescence : Strong; ruby-red