Pendant of tumbled gemstones braided in copper wire.

Gemstones, rare minerals often used in jewelry and decorative items, are known for their beauty, which is reflected in visual aspects such as color, shine, fire, transparency and lighting effects. Durability, determined by hardness, fragility/splittability and chemical resistance, is also essential. The rarity of a gemstone affects how often it occurs in nature. There are various cuts, including the cabochon, a spherical cut, and faceted cuts, in which the surface of the stone is divided into multiple facets. When grinding, characteristics such as color, color distribution, inclusions, special lighting effects, dispersion and fracture and wear surfaces are considered. Gemstones are not only popular in necklaces, earrings, bracelets and other jewelry, but also have industrial applications. Well-known examples are diamond, ruby, emerald, sapphire, aquamarine, topaz, tourmaline, amethyst, citrine, carnelian, opal, onyx, turquoise, lapis lazuli and garnet. In the 18th and early 19th centuries it was popular to make jewelry with a person's name or initials, guided by the first letter of the gemstone's name, resulting in the gemstone alphabet. In the 19th century, acrostic jewelry emerged, expressing feelings with gemstones. The best-known example is the English 'regard' ring, an engagement ring in which the word 'regard' was formed from the English names of the gemstones ruby, emerald, garnet, amethyst and diamond.