Jade, Nephrite, Jadeite - What is it exactly?

Jadeite and nephrite are materials that have both been called "jade" for thousands of years.

 

"Jade" is a cultural term used for a very durable material that has been fashioned into tools, sculptures, jewelry, gemstones, and other objects for over 5,000 years. It was first used to manufacture ax heads, weapons, and tools for scraping and hammering because of its toughness.

Then, because some specimens had a beautiful color and could be polished to a brilliant luster, people started to use jade for gemstones, talismans, and ornamental objects. Although most people who think of jade imagine a beautiful green gemstone, the material occurs in a wide variety of colors that include green, white, lavender, yellow, blue, black, red, orange, and gray.

Are All Jades the Same?

Originally, all jade objects were thought to be made from the same material. However, in 1863 a Frenchman, Alexis Damour, discovered that the material known as "jade" could be divided into two different minerals: jadeite and nephrite.

Because these two materials can be difficult to distinguish, and because the word "jade" is so entrenched in common language, the name "jade" is still widely used across many societies, industries, and academic disciplines.

In this article, the word "jade" will be used for undifferentiated materials. "Jadeite" or "nephrite" will be used when the identity of the material is known. The word "nephrite" is also an imprecise term. It is used for materials composed of the minerals actinolite and tremolite.

Physical Properties: Jadeite and Nephrite

Jadeite

Nephrite

Chemistry Silicate - pyroxene. Silicate - amphibole.
Color Usually various shades of white to dark green, sometimes gray, pink, lilac, red, blue, yellow, orange, black, colored by impurities. Usually ranges in color between white, cream, and dark green.
Streak Colorless. Colorless.
Luster Vitreous to sugary. Vitreous to silky, waxy.
Diaphaneity Translucent to opaque. Rarely semi-transparent. Translucent to opaque. Rarely semi-transparent.
Cleavage Usually not seen because of a small grain size and splintery fracture. Prismatic but usually not seen because of a small grain size and splintery fracture.
Mohs Hardness 6.5 to 7 6 to 6.5
Specific Gravity 3.3 to 3.5 3.0 to 3.3
Diagnostic Properties Color, toughness, hardness, specific gravity, grain size and habit. Color, toughness, hardness, specific gravity, grain size, and habit.
Chemical Formula NaAlSi2O6 or Na(Al,Fe3+)Si2O6 Ca2(Mg,Fe)5Si8O22(OH)2
Crystal System Monoclinic. Monoclinic.
Uses Jewelry, ornaments, tools, weapons, gemstones. Jewelry, ornaments, tools, weapons, gemstones.

 

Jadeite, Nephrite, and Artisans

Chinese craftsmen have been producing jade objects for over 5,000 years. A few hundred years ago, master Chinese craftsmen who worked with jade daily recognized that some of the jade obtained from Burma (now the Union of Myanmar) was different. It was harder, denser, worked more easily, and produced a higher luster upon polishing. It gradually became the form of jade preferred by Chinese artisans and the jade most highly prized by the Chinese people. They realized this long before scientists differentiated jadeite and nephrite in 1863.

Unknowingly, Chinese craftsmen had distinguished jadeite from nephrite and appreciated it enough to pay premium prices for jadeite. However, they didn't have the knowledge and equipment of chemistry and crystallography to distinguish them in a formal way.

Rarely, the Chinese craftsmen encountered fine-grained jadeite with a bright translucence and a rich, uniform green color. This beautiful material was given the name "Imperial Jade" and regarded as the stone of highest quality. At that time in China, ownership of Imperial Jade was reserved only for the Emperor. Now, anyone who can afford it can own Imperial Jade. The best specimens can cost more per carat than high-quality diamonds.

Jade Types and Treatments

For thousands of years, the people who manufacture and sell jade objects have found many ways to improve their appearance. Heat, wax, dye, bleach, acid, polymer injection and other treatments have all been used to improve the color, luster and stability of jadeite and nephrite. Although many of these treatments are part of traditional jade manufacturing processes, today’s serious buyers of jade want to know about all treatments that were used in the manufacturing process.

Commercial jadeite objects are placed into three “types” according to the treatments that have been used during the manufacturing process. They are designated as Type A, Type B and Type C jadeite.

Type A Jadeite

Type A jadeite objects have been treated with a coating of wax. This is the most traditional jadeite treatment. It is expected and accepted by serious buyers and generally does not impact the value of a jadeite object. In this treatment, manufacturers boil finished jadeite objects in water to clean them and prepare them for an application of wax. The objects are then dried and dipped into molten wax. The wax fills any surface-reaching pores and fractures. When the objects have cooled, excess wax is removed and the objects are buffed to a bright luster. The wax fills surface irregularities and gives the object’s surface a smooth, lustrous finish.

Type B Jadeite

Type B jadeite objects have been bleached by soaking in hydrochloric or sulfuric acid. The acid removes oxidation stains and leaches out sodium. This lightens the color of many materials. Pressure is then used to impregnate the jadeite with wax or a clear polymer resin. Impregnation fills all surface-reaching pores and fractures and gives the object an improved smoothness, luster and color.

Unfortunately, the appearance of Type B jadeite objects can begin to deteriorate in just a few years. Acid treatment makes some jadeite brittle, and polymer resins can discolor with time or exposure to heat and sunlight. Because of these problems, Type B jadeite treatment should always be disclosed when an object is sold, but many items are sold without disclosure. This lack of disclosure is because Type B jadeite objects normally sell for a small fraction of the price paid for a similar Type A object. Sellers often get away with nondisclosure because Type B treatments are difficult to detect. Testing at a gemological laboratory is often required for detection of Type B treatments.

Type C Jadeite

Type C jadeite usually has all of the treatments of Type B jadeite, but the object has also been dyed to a more desirable color. The dyes can fade over time or with exposure to heat and light. For these reasons, Type C treatments should always be disclosed.

Dye treatment can often be detected by examination with a microscope, spectroscope or gemological filters, but this testing should not be needed - the seller should disclose the full extent of treatment for every object that is sold. Disclosure doesn’t always happen because Type C jadeite sells for a small fraction of similar objects with Type B treatment.

Type C objects should be purchased for a price that assumes temporary use for a few years. Anyone who spends the serious money on jade should know the difference between jadeite and nephrite, have a good knowledge of jadeite treatments, how they impact value, and how they impact future durability and appearance. Confirmation of the jadeite type by a gemological laboratory is a good idea for expensive items. These services are easy to obtain and usually cost a tiny fraction of what is paid for a Type A jadeite item.

Jade Misnomers

A “misnomer” is an incorrect name. In the gemstone trade many misnomers have been given to materials that look like a more popular or more valuable material even though that name is incorrect. The use of a misnomer can be innocent or derogatory, but the intent is often to associate a product with one that is much more popular or more valuable. Even when done without deceptive intent, the practice can be misleading to many buyers.

An example of a jade misnomer is the use of the name “Mexican jade” for the green-dyed calcite or travertine that is commonly used to produce vases, chess pieces, desk sets and other ornamental objects. Use of the name by a seller in the presence of potential customers can be misunderstood or deceptive.

In 2015 the Federal Trade Commission announced that the next revision of their Guides for the Jewelry, Precious Metals and Pewter Industries will state that “it is unfair or deceptive to mark or describe a product with an incorrect varietal name.” [1] Once that revision is published, anyone who makes commercial use of a jade misnomer could become a fair target for civil or criminal liability. A few of the many jade misnomers are listed below.

  • “African Jade” - a massive variety of green grossularite garnet found in the Transvaal Province of South Africa
  • “Amazon Jade” - amazonite, a blue-green microcline feldspar
  • “American Jade” - californite, a variety of vesuvianite
  • “Bowenite Jade” - a variety of serpentine resembling nephrite
  • “Garnet Jade” - a massive variety of green grossularite garnet
  • “Honan Jade” - a name used for a variety of jade substitutes including jade in quartz, serpentine, soapstone
  • “Mexican Jade” - green-dyed calcite or greenish travertine
  • “Indian Jade” - aventurine quartz
  • “Korean Jade” - a variety of jade look-alikes including glass, soapstone and serpentine
  • “Manchurian Jade” - soapstone
  • “Oregon Jade” - green jasper, green grossularite or other jade look-alikes found in Oregon
  • “Serpentine Jade” - varieties of serpentine that look like jade
  • “Soochow Jade” - name used for a variety of jade substitutes including jade in quartz, serpentine, soapstone
  • “South African Jade” - green grossularite found in the Transvaal Province of South Africa
  • “Transvaal Jade” - green grossularite found in the Transvaal Province of South Africa

Early Use of Jade in Tools

People have used jade for at least 100,000 years. The earliest objects made from jade were tools. Jade is a very hard material and is used as a tool because it is extremely tough and breaks to form sharp edges.

Most jade does not have a color and translucence that is expected in a gemstone. However, when early people found these special pieces of jade, they were often inspired to craft them into a special object.

"Toughness" is the ability of a material to resist fracturing when subjected to stress. "Hardness" is the ability of a material to resist abrasion. Early toolmakers took advantage of these properties of jade and formed it into cutting tools and weapons. It was used to make axes, projectile points, knives, scrapers, and other sharp objects for cutting.

Use of Jade as a Gemstone

Jade is a durable, colorful material that can be worked into shapes and given a high polish. These properties make it a very desirable gemstone. Jade has been used to make a variety of jewelry items such as pendants, necklaces, rings, bracelets, earrings, beads, cabochons, tumbled stones, and other items.

These jewelry items are often made of solid jade, combined with other gems, or placed in settings made from gold, silver, or other precious metals. In addition to jewelry, jade is used to make small sculptures, ornaments, religious art, and small functional objects.

Other Materials Confused With Jade

A number of other minerals and materials that are commonly cut and polished are easily confused with jade. All of these materials can have a color, luster, and translucence that is very similar to jade - so similar that the average person is unable to recognize them. These materials are often used to manufacture cabochons, beads, and other objects in the same style as jade. They sometimes enter the market with and without disclosure. They are often marked with the name "jade" or with one of many misnomers.

Chalcedony is a translucent variety of microcrystalline quartz that occurs in a range of colors similar to jade. Chrysoprase is a bright green chalcedony colored by chromium that, when cut into cabochons, beads, and small sculptures, will look very similar to jade. Chalcedony occurs in a variety of other translucent colors such as black, lavender, yellow, and orange that can look like the color varieties of jade. Chalcedony can be a very close gemstone look-alike with jade. It can be differentiated from jade using is lower specific gravity and by a variety of instrumental methods.

Serpentine occurs in a variety of wonderful translucent to nearly transparent green and yellowish green colors that look very much like jade. It is a metamorphic mineral that is often found in the same geographic areas and same types of rocks as jade.Serpentine is significantly softer than jade and also has a much lower specific gravity.

Vesuvianite, also known as idocrase, is another jade look-alike that is very difficult to distinguish from jade without laboratory testing. It has similar hardness, specific gravity, and physical appearance. It is not nearly as tough as jade and will break easier - but that requires destruction of the specimen.

Maw Sit Sit is a rock with a bright chrome-green color mined in Myanmar. It has a very similar appearance to jade. Maw sit sit is composed of jadeite, albite, and kosmochlor (a mineral related to jadeite). It is used to cut cabochons, beads, and make small sculptures, and is easily confused with jade.

Hydrogrossular Garnet is a green massive variety of garnet that is usually green in color with black markings. It looks so much like jade that in South Africa, where it is common, it is known as "Transvaal Jade." It is frequently cut into beads, cabochons, and small sculptures.

Aventurine is a trade name used for a green quartz that is often colored by fuchsite inclusions. These typically color the quartz a light to dark green color and produce some aventurescent sparkle. Aventurine is sometimes confused with jade. It is sometimes referred to by the misnomer of "Indian Jade."

All of the above natural minerals and rocks can be confused with jade. Many people like them, enjoy them, and knowingly purchase them for that reason. It is important to know that these jade look-alikes, along with plastic and glass made into objects in the same style as jade, are abundant in the market place. Know what you are buying or purchase from a dealer you can trust if you are shopping for these items and desire jade instead of an alternative. Errors and deception are common.

Geography of Jade

Most people immediately think of China as the source of jade and jade objects. China has always been an important producer of jade, a leading jade cutting center, jade consumer, and jade market. The only time dominance in these activities moved outside of China was between World War II and the early 1980s. At that time the Chinese government suppressed jade commerce, and Hong Kong temporarily became the center of jade commerce.

Jade jewelry and jade artwork are extremely important in China. Jade is more important in China than the importance of diamonds in the United States. Per-carat prices for the best imperial jade in China rival the per-carat price paid for diamonds in the United States.

Since prehistoric times, jade has been used to make tools, weapons, and important ornamental objects in Asia, Europe, Australia, the Americas, and numerous Pacific islands. The toughness of jade made it an excellent material for making tools and weapons.

Because of its beauty, people held jade in highest esteem and used it to make religious art and ornaments for their rulers. None of these ancient cultures had contact with one another, yet they all independently used jade for many of their most sacred and important objects. Such is the appeal of jade.

 Author: , Ph.D., GIA Graduate Gemologist

source:

https://geology.com/gemstones/jade/

Titel Picture: Mayan jadeite: Hand-made Mayan jadeite pectoral from the Mayan Classic period. This photo was taken by John Hill and is distributed under a GNU Free Documentation License.

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