Collection: Ruby

Ruby is a gemstone belonging to the mineral corundum. Corundum that has turned red due to the presence of chromium is called ruby, while other colors are called sapphire or fancy colored sapphire.

Because chromium, the element responsible for ruby's color, is found deep underground, beautiful red rubies are not abundant. As one of the "big four" gemstones, rubies are highly recognized and popular. Pigeon Blood Ruby and Crimson Red Ruby command even higher value, but they are rare. Furthermore, due to their nature, inclusions are common, making transparent specimens particularly valuable.

Name: Ruby
Japanese Name: Kōgyoku (紅玉)
Chemical Composition: Al₂O₃+Cr
Crystal System: Hexagonal
Specific Gravity: 3.97–4.05
Mohs Hardness: 9
Cleavage: None
Luster: Vitreous
Transparency: Transparent to Translucent (almost opaque)
Refractive Index: 1.762–1.770
Birefringence: 0.008
Coloration: Red-based
Dispersion: 0.018