Aquamarine has been the traditional birth stone for the month of March although some jeweler's charts list bloodstone as an alternate. Aquamarine ranges from pale blues to light blues to yellowish blues. Aquamarine is the mineral Beryl, a Beryllium Aluminum Silicate with the general chemical formula Be3Al2(Si16O18). Beryl crystallizes in the hexagonal system, it ranges in hardness from 7 1/2 to 8 on Moas scale; it has an imperfect cleavage and a vitreous luster. Optically, beryl is uniaxial negative; some specimens may be strongly diachronic; its refractive index ranges from about 1.57-1.58 or to 1.58-1.59.