The English name of ruby is Ruby, derived from the Latin word Ruber, meaning red. The mineral name of ruby is corundum.

The chemical composition of ruby is aluminum oxide (Al2O3), which turns red to pink due to the trace element chromium (Cr3+). It belongs to the tripartite crystal system. The crystal morphology is often barrel shaped, short column shaped, plate shaped, etc. Aggregates are mostly granular or dense blocks. Transparent to semi transparent, with glass luster. The refractive index is 1.76-1.77, and the birefringence index is 0.008-0.010. Obvious dichroism, heterogeneous. Sometimes it has a special optical effect - the starlight effect, which will reflect charming six rays of starlight under the illumination of light, commonly known as the "six lines". The hardness is 9, and the density is 3.95-4.10 grams per cubic centimeter. No cleavage, developed cleavage. Ruby emits red and dark red fluorescence under long and short wave ultraviolet radiation.

Among the reds of rubies, the most valuable is the gemstone with the strongest color, known as "pigeon blood", which is very precious. This bright and intense color, which can almost be called deep red, reveals the true face of ruby at a glance. Unfortunately, most rubies are light in color and have a pink feel, so rubies with a dove blood tone are more valuable. Additionally, due to the intense vitality and vibrant colors that permeate ruby, people in the past believed it to be the incarnation of a dead bird and eagerly fantasized about it. The origin of natural rubies is rare, and high-quality rubies are only produced in Myanmar, and production is gradually decreasing. It can be said that they have almost declined, and large stones no longer appear.

Evaluation and purchase of rubies. The primary evaluation and purchasing factor for ruby is color, followed by weight, transparency, and clarity. Generally speaking, faceted rubies with pure color, large particles, transparency, no or very few inclusions and defects, fine processing, and symmetrical proportions of each part are considered top quality. Myanmar ruby, mostly in pigeon blood red, has a uniform color, high transparency, large particles, and very few flaws and cracks. Sri Lankan ruby, light in color, mainly starlight ruby. Thai pointed bamboo patterned ruby, deep red, not very bright in color, relatively clean. Ruby has brittleness and is afraid of knocking or falling. It should be worn with caution.