gemstone or gem (also called a preciousor semi-precious stone, a fine gem, orjewel) is a piece of mineral, which, in cut and polished form, is used to make&n, which, in cut and polished form, is used to make jewellery or other adornments.ks (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.

Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value.

Rarity is another characteristic that lends value to a gemstone.

Apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms.

The carvings of Carl Fabergé are significant works in this tradition.