Jade
“Jade” is a generic term for nephrite, jadeite, and under certain conditions green omphacite. In China, a pierced jade disk is a symbol of heaven.
OVERVIEW
ABOUT JADE
Jade has its cultural roots in the smoke-dimmed caves and huts that sheltered prehistoric humans. Around the world, Stone Age workers shaped this toughest of gems into weapons, tools, ornaments, and ritual objects. Their carvings invoked the powers of heaven and earth and mystic forces of life and death.
BIRTHSTONES & ANNIVERSARIES
Jade is the official gem for the 12th anniversary.
CONFUCIUS
The philosopher wrote that jade is like virtue and its brightness represents heaven.
BI
The traditional jade flat disc with a hole in the middle, known as a “bi,” symbolizes heaven.
YU
The character for jade is one of the oldest in written Chinese, dating to 2950 BC.
FACTS
Mineral: Jadeite, Nephrite, Green Omphacite
Chemical composition:
Jadeite: NaAlSi2O6
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2
Omphacite: (Ca,Na)(Mg,Fe2+,Al)Si2O6
Color: Green, white, orange, yellow, lavender, black
Refractive index: 1.666 to 1.680 (+/-0.008) and 1.606 to 1.632 (+0.009, 0.006)
Birefringence: Usually not detectable
Specific gravity: 3.34 and 2.95
Mohs Hardness: 6.5 to 7 and 6.0 to 6.5
TREATMENTS
There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.
SYNTHETICS
Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.
IMITATIONS
Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.
WHY WE LOVE THIS GEMSTONE
1
Interaction with Light
Jadeite’s structure scatters light. If properly cut, a white piece with a small green spot will make the gem appear completely green if lit from behind.
2
Tough, But Not Hard
Not unusually hard for a gem, both jade types are extremely tough. Neolithic knives and axe heads were often made of nephrite.
3
Musical Jade
Nephrite rings musically when struck. The imperial court in China had jade wind chimes designed to ring specific notes.
QUALITY FACTORS
For both jadeite and nephrite, green is the most valued color. Semi-transparent clarity and fine texture also increase jade’s value dramatically.
COLOR
The finest jadeite—almost transparent with a vibrant emerald-green color—is known as “imperial jade.”
TRANSPARENCY
Jadeite’s transparency ranges from completely opaque to semi-transparent. The best jadeite is semi-transparent.
TEXTURE
Jadeite has a lovely, smooth, and even texture that makes people want to touch and hold the gem.
CUT
While jade is rarely faceted like other gems, plain as well as intricate jade carvings are judged by their artistry.
CARAT WEIGHT
Jadeite is generally sold by the piece rather than by weight. For top-quality imperial jadeite, slight size differences can make large value differences.
JADE Quality Factors: The Comprehensive Guide
RESEARCH
Explore sources, gemological research, and the role of gems in history.
Tao Hsu and Andrew Lucas , Aug 14, 2014
llaria Adamo, Valeria Diella, Rosangela Bocchio, Caterina Rinaudo, and Nicoletta Marinoni , Apr 28, 2016
RECOMENDED READING
California Jade: The Geologic Story of Nature's Masterpiece
Donald L. Dupras
The John Sinkankas Jade Symposium : April 21, 2007
John Sinkankas Memorial Symposium
Jadeite Jade: A Stone & A Culture
C. M. Ou Yang
