hardstones

Hardstones are a loose, trade term for durable, compact stones and rocks that take a high polish and are suitable for carving, bead making, and inlay work. They are not a formal mineralogical category but rather a practical grouping used by lapidaries to distinguish them from softer stones such as soapstone or limestone. Hardstones are typically silicate-based and include chalcedony varieties (agate, carnelian, onyx, jasper), nephrite and jadeite (jade), obsidian, and other dense, fine-grained materials such as chert or petrified wood.

Characteristically dense and finely textured, hardstones can be cut, ground, and polished to a high luster. They occur in a range of colors and patterns, often due to mineral impurities. Because of their toughness and polishability they are widely used for cabochons, beads, cameos, intarsia, and small carvings.

Treatment and care: Some hardstones are subjected to heat, irradiation, or dyeing to enhance color or uniformity; jade can be treated with heating in some traditions. Such treatments should be disclosed when marketed. Stability varies by material, and care guidelines depend on the specific stone and any treatments it has received.

History and use: Hardstone carving has a long history across many cultures, including ancient China, India, Central Asia, and the Mediterranean. The term remains common in jewelry and the craft trade, though newer classifications use more precise mineral names.