White gold :
White gold is an alloy of pure gold with copper, Zinc, Palladium or nickel.
Carat :
The carat (ct) is a unit of mass equal to 2 g. Carat is used for measuring the weight of gemstones.
Aquamarine :
Blue variety of Beryl (Silicate). Aquamarine is named after it's bleu color similar to the blue of the sea. It is a different gemstone than blue Topaze.