AQUAMARINE - (Specific gravity - 2.70, refractive index - 1.57)

Aquamarine is a lovely greenish-blue stone, which is absolutely clear and transparent. These stones also belong to the Beryl group and come under the precious category. The real good quality stones are not easily available. Aquamarines are good substitutes for the Emerald. Their weight should be at least two carats. Generally set in Silver, they are to be worn on the little or middle finger.

Aquamarines come under the category of secondary precious stones, therefore they can be expensive. A blue Topaz can be similar in colour and appearance to that of a Blue Aquamarine, and can be mistaken as one. Their properties are different. While the Aquamarine is a fairly good substitute for the Emerald, a Blue Topaz is only good as a jewelery.