In the sixteenth century, Spanish conquistadors learned of a stone worn by Mesoamericans as an amulet to cure colic and similar maladies. The Spanish called it piedra de la yjada (in Latin, lapis nephrictus), meaning “stone of the loin,” and brought fine examples back to Europe. In translation from Spanish to French, the phrase was misprinted as pierre le jade.
In the mid-seventeenth century, the New World sources had disappeared, and Europeans forgot the material but not the name; they applied it to the stone of numerous carvings arriving from China. In 1780, geologist A.G. Werner described the traditional Chinese carving material and labeled it nephrite, after the Latin term. In 1863, French chemist Augustin Damour chemically analyzed a Chinese carving of a somewhat harder stone and found it was different from nephrite. He labeled this material jadeite, derived from the “original” term jade. It was also learned that the nephrite stones were sourced in China proper, whereas the jadeite was sourced from northern Burma (Myanmar). In 1881, Damour discovered that Burmese jadeite and the original Mesoamerican material were mineralogically identical. Nevertheless, the common term jade persists for both jadeite and nephrite. To make matters even more complicated, other stones that appear similar or have been used in similar manner in ancient cultures are also simply called “jade.” Such is the confusion with the most important ornamental gemstone.
The special quality that nephrite and jadeite jade share is exceptional durability; nephrite is one of the toughest substances. Both rarely yield to a hammer blow—a convenient field identification technique (obviously not suggested for art or artifacts.) This property means that jade can be carved into remarkably fine and intricate forms with minimal risk of breaking.
The differences in quality and prices of jade are great. Color and translucency are the major considerations in evaluating both nephrite and jadeite. Most of the jadeite mined is used as so-called utility grade for making bathroom tile. The rarest and most valued color for jadeite is pure, even, and intense emerald green. When this color is combined with maximum translucency and smooth, uniform texture, the stone—known as Imperial jade or fei tsui—commands an extremely high price.
This blog post is an excerpt is from the 25th-anniversary edition of Gems & Crystals From One of the World’s Great Collections by George E. Harlow, curator in the Department of Earth and Planetary Sciences, and gemology expert Anna S. Sofianides, featuring photography by Erica and Harold Van Pelt, published this month by Sterling Publishing Company.