PIAGET, YELLOW GOLD WITH NEPHRITE DIAL, REF. 9031

Both nephrite and jadeite are part of the jade family. Although similar, the two stones have different physical and chemical characteristics. While nephrite jade possess mainly greys and greens (and occasionally yellows, browns or whites), jadeite jade, which is rarer, can also contain blacks, reds, pinks and violets. Nephrite jade is an ornamental stone, used in carvings, beads, or cabochon cut gemstones.

The name nephrite is derived from lapis nephriticus, which in turn is derived from the Greek word for 'kidney stone' and is the Latin and Greek version of the Spanish piedra de ijada (the origin of "jade" and "jadeite"). Accordingly, nephrite jade was once believed to be a cure for kidney stones

Jade has been used as the base for carving since the prehistoric times. As jade is such a hard material, it was able to be used for weapons such as knives and tools for edging. Once other materials were discovered for tools, jade became used for more ornamental than utilitarian purposes.

In the early Chinese dynasties, jade (or nephrite jade) was used for utilitarian and ceremonial objects including jade burial suits and was considered the "imperial gem."