Gemstones

特許 権利維持 A gemstone or gem (also called a fine gem, jewel, precious or semi-precious stone) is a piece of crystal (mineral), which, in cut and polished form, is used to make jewelry or other adornments.[1][2] However, certain rocks (such as lapis lazuli) or organic materials that are not minerals (such as amber or jet), are also used for jewelry, and are therefore often considered to be gemstones as well.