Nephrite and Jadeite
Do you remember the first time you saw your favorite gemstone? Or when you fell in love with it? Jade is actually important to me because it is my husband’s favorite gem. He fell head over heels for jade in Tucson because of it’s allure and his love of Chinese history, and ever since he has inspired me to get my hands on it as much as I can. While it’s a stone I never disliked, I didn’t have any emotional connection to it until I saw how much he loved it. Since opening my eyes to this beauty, I’ve seen exquisite pieces that I would have never looked for before.
It’s no wonder so much confusion surrounds the word, as this stone’s mystery has captivated people from almost every continent for thousands of years. The semantics of jade are tricky, as the term can refer to either or both jadeite and nephrite, two distinctly different minerals with different properties. Throw in all of the misnomers to trick people into buying jade imitations, add in the misleading names for treated jade, and you’ve got yourself a lot of misinformed consumers and countless misconceptions about the characteristics of “jade.”
What makes jade so interesting is of course the allure of it’s color and texture, it’s rich history, and it’s significance to a multitude of cultures. History tells us that people have fought and died for both nephrite jade and jadeite jade, some ancient peoples and some more recent than you might like to believe. The Imperial Seal, carved of nephrite jade, determined imperial power and was invaluable to the Chinese people for thousands of years. Nephrite is tougher than steel, and was long believed to have medicinal qualities. Who wouldn’t be fascinated with this geologically unique and historically impactful gemstone?
Moving forward in this article, I will not use the word “jade” unless referring to both nephrite and jadeite at the same time. If I’m talking about nephrite jade, I will say nephrite. If I’m talking about jadeite jade, I will say jadeite.
This article will answer a few common and some not so common questions about jade: How are jadeite and nephrite different? What is “Imperial Jade?” Is there such a thing as cat’s-eye jade? and more. Keep in mind moving forward that the “jade” of Chinese antiquity and religion is in fact nephrite. Nephrite is more plentiful and not as fine as fine jadeite. They do look different, because they are different.
It’s Not Easy Being Green
In the West, we think of nephrite and jadeite always as green. I’ve heard the term “lavender jade” passed around in jewelry stores, but usually when someone asked for jade they meant, without saying, green nephrite or green jadeite. Nephrite and jadeite are both naturally white and their colors come from the presence of other minerals in the stones.
Colors of Nephrite: translucent to opaque. pure white, shades of gray, yellow, red-brown, blue-green, green, green-black, black
Colors of Jadeite: translucent to opaque. pure white. shades of gray, yellow, red-brown and other reds, lavender, blues and purples, blue-green, green, and green-black
Pink and blue are also rare colors that might show up in nephrite and jadeite.
Historically speaking, nephrite jade in China was most valued in white. It is said that porcelain was actually invented by the Chinese to mimic jade, as they may have been searching for an alternative material that would be easier to obtain and work with. While nephrite and jadeite both come in a variety of colors and there are plenty of other ways to gemologically identify them, it’s believed they can be distinguished by “feel.” I recently read an enthralling book called “Jade: Stone of Heaven” written by Richard Gump in 1962. This author, Gump, was an established authority on jade and I have stumbled upon multiple sources that claim he was able to identify jade by feel after losing his eyesight in later years.
As Old as the Hills.
Nephrite has been important to China for thousands of years. No other gemstone has ever played such an important role in religion, and especially not for so long. The Chinese do not call it “jade” or “nephrite,” they call it yù 玉, a term which has existed for about 5,000 years and generally means a “precious stone of great beauty.”
Archaeologists have found nephrite artifacts from China dating back to the Neolithic period, which ended around 2000 BC. I was particularly delighted to find out that a couple of ancient nephrite pieces are actually in a museum in Kansas City. The bird pictured here is believed to have been carved in the 2nd or 3rd millenium BC.
On the other side of the world, history tells us about the cultural significance of the “other” jade. Pre-Columbian civilizations in Mexico, Central and South America used jadeite for medicinal purposes, funerary practices, religious objects, dishes, weapons, tools, jewelry, the list goes on! In fact, Pre-Columbian people believed about jadeite the same thing that the Chinese believed about nephrite: that it was the key to immortality.
Much later, the Maoris of New Zealand used nephrite in weapons, tools, and jewelry, valuing nephrite (or as they called it, pounamu, meaning “greenstone”) above all other stones.
Before we even knew what it was, civilizations around the world knew and loved the stones we call “jade.” Richard Gump said it best in his book, Jade: Stone of Heaven: “The Central Asians placed a huge slab of jade before the tomb of Tamerlane to make it inviolate. The pre-Columbians made sacrificial knives from it. Aladdin expressed wonder at the fabulous trees of jade in the underground cavern. The Russians carved a whole sarcophagus, for Czar Alexander III, of jade. In both New Zealand and New Caledonia a jade mere or war club was the chief’s symbol of authority. Fathers in the Loyalty Islands once bartered their daughters for jade. China built a civilization around the stone.”
Most sources group Nephrite and Jadeite together to say that the “toughness of jade” is “exceptional.”
Well first of all, they are different gemstones and have different toughnesses. Secondly, “exceptional” to the layman doesn’t begin to explain the durabilty of either stone. While their toughness rating may be different, they are both indeed exceptionally resistant to breaking. Keep in mind that hardness and toughness are different: hardness is resistance to scratching.
There is a system of measuring toughness, and while it seems complicated, understanding the toughness of nephrite and and jadeite is simple. According to the fracture toughness scale, which measures the work required to separate two surfaces of a crystal along a certain crystallographic plane (GIA. https://4cs.gia.edu/en-us/blog/more-than-mohs-scale-gem-durability/ ) toughness is measured in Ergs.
The toughness value of corundum measures 600 ergs/cm.
The toughness of diamond measures between 5,000 and 8,000.
The toughness value of jadeite is 120,000.
And the toughness value of nephrite…drum roll please…
is around 225,000 ergs/cm.
So diamond’s toughness is rated “good,” and nephrite is still 28 – 45 times tougher than a diamond. Don’t be confused though, diamond is still one of the hardness natural substances on Earth. Remember, hardness is resistance to scratching.
Diamond’s hardness is a 10 on the Mohs Scale, whereas nephrite is a 6 – 6 1/2, and jadeite is a 6 1/2 to 7.
Too much to remember?
Jadeite is harder than nephrite. Nephrite is tougher than jadeite. They’re both tougher than diamond, but neither one is as hard.
If you’re wondering about jade for daily wear, I say wear it but be careful. It’s important to mention that “Usually, a razor blade will not scratch nephrite.” Handbook of Gem Identification, Liddicoat.
In Your Element.
I recognize that there is confusion, even among professionals, regarding the chemistry of jadeite and nephrite. So here’s the skinny:
Jadeite and Nephrite are separate species. They have different properties and a different appearance.
They are both crystalline. They are both aggregates, meaning they are made up of a number of individual crystals. When my friends tell me that all gemstones are rocks, I correct them. Rocks are aggregate. Lapis Lazuli is a good example of an aggregate, as it is usually composed of calcite, sodalite, and pyrite.
Pyroxene? Amphibole? What?
Amphibole is the name of a supergroup of minerals. Pyroxene is the name of another supergroup of minerals. This might help you make sense of the term: garnet and tourmaline are both supergroups. Like other mineral groups and supergroups, there can be wide variations in chemical composition meaning that not all amphibole minerals have the same properties or appearances. Interestingly enough, the amphibole group is actually pretty similar to the pyroxene group. Completely unrelated and off topic: If you’re interested in these mineral groups, research one of the most famous amphiboles: Asbestos.
Nephrite is not technically it’s own “mineralogical variety,” it’s a variety of actinolite or tremolite. Nephrite varies depending on how much of it is tremolite and actinolite and what it’s mineral impurities are.
It’s actually pretty complicated stuff, just check out what GIA has to say about it: “Nephrite is mainly composed of tremolite, Ca2Mg5[Si4O11]2(OH)2, and a variable amount of actinolite, Ca2 (Mg, Fe)5[Si4O11]2(OH)2. When the Mg2+/(Mg2+ + Fe2+) ratio is 0.91 or higher, the main mineral is tremolite; when the ratio is less than 0.91, it is actinolite (Bragg and Claringbull, 1965; Wang et al., 1982; Leake et al., 1997). ” GIA, https://www.gia.edu/gems-gemology/summer-2017-mg-fe-nephrite
What is “cat’s eye jade” and is it really jade?
I’ve seen this on the Internet and occasionally at shows. A beautiful, bright green chatoyant gem calling itself “cat’s eye jade.” Is it nephrite? Is it jadeite? Well…Technically it’s neither, but it is definitely closest to nephrite. For the record, I have also seen this vibrant stone marketed as “cat’s eye nephrite” and while that’s not far off, it’s not totally accurate. Why does it matter whether it’s nephrite or not? Because this chatoyant gem posing as jade is actually not nearly as tough and should be handled with much more care. Would I still buy one? In a heartbeat.
Here’s the research:
Handbook of Gem Identification, Liddicoat: “Sometimes the felted structure of nephrite grades into zones of actinolite with a parallel orientation of crystals. This may give an excellent chatoyant effect in a cabochon, but it has the fragility of actinolite instead of the toughness that the matted structures gives to nephrite. This material is properly called actinolite cat’s-eye.”
The Jade Enigma, Jill M. Hobbs: “A chatoyant material known as “cats-eye nephrite” surfaces occasionally in the jewelry trade. It belongs to the tremolite-actinolite series of amphiboles, or which nephrite is a variety. The chatoyancy is due “to the fibrous structure and to the preferred orientation of tremolite fibers.” [Tan et al., 1978]. Therefore, it has been suggested by some (see Anderson, 1980) that the material should be called “cat’s-eye tremolite.” Yet, the matieral is more apt to be actinolite than tremolite.” … “…either tremolite of actinolite cat’s-eye is more appropriate than “cat’s-eye nephrite,” because the chatoyancy is due to the reflection of light off parallel fibers, and by definition nephrite consists of randomly oriented, interlocking fibers.”
Why are nephrite and jadeite both called jade?
Well they look similar, for one. The technology for identifying minerals is newer than both of them.
Burma (which had known about jadeite for a while but interestingly did not choose it over nephrite for religious or ritual purposes. They only used nephrite.) began selling jadeite to China in 1784. That means that prior to 1784, the only “jade” to the Chinese was nephrite. In fact, the Chinese recognized that this “Burmese jade” wasn’t the same as Chinese jade, and were careful to distinguish between the two minerals by using different terminology. Nephrite was called yù and the Burmese jadeite was called fei-ts’ui meaning “kingfisher jade,” which was a term that had previously been used to denote a very specific shade of green nephrite from Khotan. Chinese consumers did not accept jadeite for another hundred years, as even though no scientific distinction was yet made, it was clear to the Chinese that the appearance and “feel” made the “Burmese jade” different from the nephrite to which they were accustomed.
The scientific distinction was not made until years later, when Professor A. Damour discovered and documented the difference between the two jades and coined the term “jadeite” in 1863.
Other Jade Terms
These are by no means all of them or even close, but here are some common jade terms you might hear in a jewelry store and what they really mean.
Imperial Jade is a trade term, not a geological or gemological term. There isn’t an exact science dictating the specific chemical makeup of “imperial jade” over other jade. As far as I know, the FTC does not have restrictions on what can and can’t be called “imperial jade”–so if your shopping for it, make sure that the salesperson knows what they’re talking about. “Imperial Jade” is a term that should only be used for the exceptionally fine quality jadeite: almost transparent with a vibrant emerald green color, according to GIA.
Can jade be treated? Oh yeah. Jadeite has been treated with dye since at least the mid 1900’s. Here are some terms (that your salesperson should disclose) to indicate the gem has been treated:
Unlike ‘A’ Jade which is natural and untreated, ‘B’ Jade is jadeite that has been bleached and impregnated with polymer.
C Jade has been bleached, dyed, and impregnated with polymer.
Pretty old school. D Jade has been dyed, but it hasn’t been impregnated with polymer.
Conclusion and References
I hope this has helped answer some of your questions about jade, and more importantly I hope it has inspired you to dig deeper into your gemological research. Whether you work in the industry or you simply want to be an educated consumer, there are always exciting things to learn about gemstones.
The Jade Enigma by Jill M. Hobbs, GIA https://www.gia.edu/doc/The-Jade-Enigma.pdf
Jade: Stone of Heaven by Richard Gump
Handbook of Gem Identification by Richard T. Liddicoat, Jr
Materials from the GIA Colored Stones course