Rubies, the birthstone of July, are considered the king of gems and represent love, health and wisdom. It was believed wearing a fine red Ruby bestowed good fortune on its owner. A Ruby is the most valuable gemstone and its value increases based on its color and quality.
Luster: Vitreous, Adamantine
Birthstone Zodiac sign: Cancer
Associated Month: July
Crystal system: Hexagonal central system
Chemical formula: Al₂O₃
Hardness (Mohs hardness scale): 9
Close in likeness is the Garnet, though usually darker. I've included those in the following pieces.