gemstone

A selection of gemstone pebbles made by tumbling rough rock with abrasive grit, in a rotating drum. The biggest pebble here is 40 mm long (1.6 inches). A **gemstone** or **gem** (also called a **precious** or **semi-precious stone**, or **jewel**) is a piece of [|mineral], which, in cut and polished form, is used to make [|jewelry] or other adornments.[|[1]][|[2]] However certain [|rocks], (such as [|lapis lazuli]) and [|organic] materials (such as [|amber] or [|jet]) are not minerals, but are still 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 [|lustre] or other physical properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone. Apart from jewelry, from earliest antiquity until the 19th century [|engraved gems] and [|hardstone carvings] such as cups were major luxury art forms; the carvings of [|Carl Fabergé] were the last significant works in this tradition.