A gemstone is a rare precious and durable mineral organic material or rock which can be cut and polished to be used in jewelry and other decoratives. In the market gemstones can be found in different colors shape and size. Hypnotic gems 2 pounds brazilian tumbled polished natural stones assorted mix large size 1 25 to 1 75 average 1 5 4 5 out of 5 stars 960 19 99 19.