Ruby

Ruby belongs to the mineral species corundum, which includes sapphires.  In GIA terms, only a sapphire with red as its dominant hue can be called a Ruby, while the pink color varieties are called pink sapphires.  

Ruby comprises one of "The Big Three" alongside emerald and sapphire as the most highly sought after gemstones.  The highest priced rubies come from Myanmar and the most desirable color is pigeon's blood.  Most rubies are heated to enhance their color.  Unheated rubies command a much higher price than heated ones.  

Ruby is the birthstone of July.