Sapphires are the most commonly known gem that is blue. Aquamarine and topaz are also blue, as are lapis lazuli, opal, and agate. Other lesser known blue stones are chalcedony, sodalite, spinel and azurite.
Sapphires are blue in color and it is the most popular blue gem around and it is also the birth stone for september. Lapis Lazuli is a nice blue as well.
