There are several gemstones that are always blue or contain blue shades. Some of these gems are birthstones, associated with a certain month of the year and an appropriate gift for those born in that time frame.
Aquamarine, the birthstone for the month of March, acquired its name from its light blue color. This hard type of a mineral called beryl has a color that resembles seawater and is common in many types of jewelry.
Sapphires are typically blue but also come in other colors. However, this September birthstone gets its name from the Latin "sapphirus," which in essence means blue.
Tourmaline comes in a wide selection of colors, including shades of blue. People associate this gem with love and friendship and, according to legend, possesses the ability to calm its wearer.
Blue topaz is such a common gem available in a huge array of shapes and cuts. It is translucent and very hard, with a rating of 8 on the Moh's scale.
Tanzanite, discovered in the African nation of Tanzania in the 1960s, is a violet-blue gem. Turquoise is a common blue stone that ranges from opaque to translucent. Both turquoise and tanzanite are December birthstones.