Sterling silver is an alloy of silver containing 92.5 by weight of silver and 7.5 by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
Gold-filled jewelry is composed of a solid layer of gold, which must constitute at least 5% of the item's total weight, mechanically bonded to sterling silver.
A gemstone (also called a gem, fine gem, jewel, precious stone or semi-precious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli) or organic materials that are not minerals (such as amber, jet, and pearl) 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.