Carnelian agate silver signet ring of approximately 12 carats

Carat : The carat (ct) is a unit of mass equal to 2 g. Carat is used for measuring the weight of gemstones.
Sapphire : Sapphire is a gemstone of the family of the mineral corundum. The most famous color for Sapphire is blue, but trace amounts of other elements can give yellow, purple, orange, or greenish sapphires. In the case of chromium impurities in corundum it would be called a called a Ruby. Sapphires are found in Sri Lanka, Myanmar or Australia.
Cabochon cut : Means a polished dome shaped gemstone stone, without facet.