Blue sapphires come in various hues, from pale baby blue to rich royal blue. Blue sapphires are the most popular sapphire color, although numerous colors exist. Many royal engagement rings have included blue sapphires. Blue sapphires are colored by trace amounts of titanium and iron. Greater amounts of these minerals increase the level of color saturation. High quality, untreated blue sapphires are extremely rare and valuable. Blue sapphires are found in a number of locations around the world including Kashmir, Myanmar, Sri Lanka, Madagascar, Thailand, Australia, Tanzania, and the state of Montana in the United States.