Jade is an ornamental stone. The term jade is applied to two different metamorphic rocks that are made up of different silicate minerals:

The English word jade (alternative spellings "jaid", "jadeite") is derived (via French l'ejade and Latin ilia) from the Spanish term piedra de ijada (first recorded in 1565) or "loin stone", from its reputed efficacy in curing ailments of the loins and kidneys. Nephrite is derived from lapis nephriticus, the Latin version of the Spanish piedra de ijada. In some countries, jade is more commonly known as 'greenstone'.

Nephrite and jadeite were used from prehistoric periods for hardstone carving. Jadeite has about the same hardness as quartz, while nephrite is somewhat softer. It was not until the 19th century that a French mineralogist determined that "jade" was in fact two different materials^{[citation needed]}.

Among the earliest known jade artifacts excavated from prehistoric sites are simple ornaments with bead, button, and tubular shapes. Additionally, jade was used for adze heads, knives, and other weapons, which can be delicately shaped. As metal-working technologies became available, the beauty of jade made it valuable for ornaments and decorative objects. Jadeite measures between 6.0 and 7.0 Mohs hardness, and Nephrite between 6.0 and 6.5, so it can be worked with quartz or garnet sand, and polished with bamboo or even ground jade.^{[citation needed]}