Ruby celebrates the birthday of those born in the Month of July. Shakespeare mentioned rubies several times in his various writings and you are referred to the classic reference by George Frederick Kunz for the remainder of these.
Fine rubies are probably one of the world's rarest gems.
If you were to walk into any jewelry store, the jeweler could probably show you many fine diamonds but probably only a few fine rubies. Only diamonds and a few manufactured abrasives such as boron carbide and silicon carbide are harder. There are three crystallographic axes of equal length that intersect one another at 120 o and a fourth longer axis that is perpendicular to the other three. Ruby as all other varieties of corundum is very tough. It shows no cleavage but the crystals sometimes exhibit a basal parting.