Shades of jade: Are you selling the real deal?

by charlene_voisin | August 1, 2012 9:00 am

By Branko Deljanin

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Jade is a commercial term encompassing green, white, black, and yellow-brown jadeite and nephrite. The world nephrite jade market is estimated at more than 1000 tonnes per year, with half the supply originating from British Columbia. Just as Canadian diamonds are a source of national pride, the same is true of Canadian jade. Yet, with only 20 per cent of the material mined of gem quality, misrepresentation and non-disclosure are very real possibilities.

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At the GJX show in Tucson earlier this year, World Gem Society (WGS) president Robert James reported some Chinese dealers selling what they called ‘Canadian Jade’ (Figure 1). This material was said to be virtually identical to known Canadian nephrite jade. A closer look under a 10x microscope, however, revealed it to be dyed quartzite (Figure 2, page 2). At a fraction of the cost of true Canadian jade, it won’t be long before this material makes its way through the supply chain in large quantities.

Last year at our lab in Vancouver, we received a necklace of green beads for testing (Figure 3, page 2). Our client bought it believing it was natural jadeite jade, and wanted an appraisal for insurance purposes. The colour looked good and visually, it appeared to belong to the jade family—it had a very high translucency usually associated only with the highest-quality jade.

Upon closer examination, we noticed a concentration of colour around the grains. We also found it had a low spot refractive index (RI) of 1.55. (Nephrite jade’s RI is 1.61, while jadeite jade’s is 1.66). We informed the client the gemstone was not jade, but rather dyed quartzite. As you can imagine, he did not return to pick up the necklace, and we now use it as an example in our lectures and training workshops.

With what might be an influx of Chinese ‘Canadian jade’ hitting the market, an overview of natural jade’s properties may be in order.

Breaking down jade sources

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Nephrite jade is a silicate of calcium and magnesium, and prized for its extreme toughness (it is the toughest of any natural gemstone), its alluring translucency, and smooth polished feel. Its colour ranges from pure white to all shades of green, yellow, and black.

Canada is home to one of the largest producers and exporters of this material, with three mines in northern British Columbia, about 100 miles east of Alaska’s border (Figure 4). Nephrite is also found in the Yukon, but there has been no production from that area in the past five years.

Kirk Makepeace, owner of B.C.’s Jade West, a Canadian nephrite producer, estimates about 7000 tonnes of jade have been exported from Canada in the last 30 years, resulting in a steady supply of a stone once reserved exclusively for the Emperors of China. Today, the bulk of Canada’s jade production is used for traditional jade carvings and jewellery mainly in China, Taiwan, and New Zealand.

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Russia produces two types of nephrite jade: white and green. Much of what is sold at premium prices in China as Hotian Yu (i.e. Chinese white nephrite) is really of Russian origin and difficult to distinguish from Chinese jade. Siberian white jade is also mistaken for Hotian Yu, hence its dramatic increase in value in the past few years.

Although most Russian green nephrite is virtually indistinguishable from Canadian jade, one deposit—known only as ‘#7 mine’—may actually surpass our homegrown material. In its highest grade, nephrite from this deposit is devoid of black and/or green spots. Unfortunately, the deposit is reportedly almost exhausted, and green nephrite buyers from China are now looking for the only alternative that is still available, gem-grade Canadian green nephrite. Additionally, Russia is perceived as a somewhat unreliable source, given certain export restrictions and the difficulty of getting permits, which makes legal mining very difficult to do.

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Chinese nephrite jade—also known as ‘Stone of Heaven’—has been revered in China for more than 5000 years. Hotian town is bisected by the famous White Jade River, the historic source of the best white jade in China. Jade prospectors typically pan in the rivers to collect jade pebbles. Famed Hotian white nephrite surpasses gold in value, while natural white nephrite ‘nuggets’ sold throughout Shanghai and Guangzhou sell for $2000 to $10,000 apiece. If the material can be confirmed as Hotian, the best white is considered ‘whiter’ and commands the highest prices. Unlike gold, this stone is sold not by weight, but rather colour, shape, and size. Many pieces are in the 1-oz to 5-oz range, thus the comparison to it being more valuable than gold. The white ‘cabbage’ jade from China’s Qing Dynasty (1644 to 1911) seen in Figure 5 (page 3) is valued at $900,000 US.

Myanmar (formerly known as Burma) has produced the best-quality jadeite jade for centuries, and its production ranks first in the world. The country has both primary deposits without skin and secondary, better-quality boulders. Although the government holds jade auctions in Rangoon, most jadeite produced in Burma is sold illegally into China and Thailand.

Guatemala is another source of jadeite jade. Mesoamerican cultures paralleled China in their devotion to this stone, using it for ceremonial worship. Japan and the United States are two other sources, but the average quality is considered only fair.

Jade simulants

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Slightly harder though not as tough, green jadeite jade is most commonly confused with nephrite jade. A relatively new material, it was introduced to China from Burma in 1784 and is often mislabelled as ‘Chinese jade,’ since prior to 1951 there was no clear border between China and Burma. At the time, it was presumed the jadeite had actually been found in the Yunnan province of China.

While many green translucent gems like serpentine or chrysoprase look like jadeite and nephrite to the naked eye, their gemmological properties are quite different and easily identifiable based on RI, under magnification (Table 1, page 6), and using visible and infrared spectroscopy.

Omphacite and jadeite have long been considered easily distinguishable from one another, although the former is typically a dark green to black material that has higher optical properties. While standard gemmological properties may indicate jadeite, omphacite’s texture is slightly more granular than normal. The Gemological Institute of America (GIA) and other major labs are using Raman spectroscopy to distinguish jadeite jade from omphacite, but Canadian labs have not yet encountered any such specimens.

Identifying jadeite jade using standard and advanced instruments

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Standard instruments like refractometer, microscope, and spectroscope can be used to identify material as jadeite jade based on its refractive index of 1.66, characteristic granular interlocking structure, visible spectra of 437 nanometer (nm) (due to iron), and fine lines at 690 nm (due to chromium) in the case of the green variety. Advanced instruments (i.e. infrared and visible spectrometer) are necessary to determine whether the colour of jadeite jade is natural or treated.

Seen in Figure 6, a Fourier transform infrared spectroscopy (FTIR) is a powerful tool for identifying the types of chemical bonds found in gems by producing an infrared absorption spectrum that is like a molecular fingerprint. It is used in gem labs to distinguish natural colour from polymer-treated jade, as well as identifying the natural or synthetic origin of diamonds and other gemstones.

UV-visible-NIR spectrophotometer measures how a gem absorbs light in the 200- to 1100-nm range and is used in gem labs for the detection of:
• gem variety (i.e. to distinguish nephrite from jadeite jade); and
• colour origin (i.e. natural colour versus dyed jade).

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Also known as ‘A’ jade, natural-coloured jadeite jade is the rarest and most valuable type of this material. Without impurities, jadeite is white, but it can also be lavender (due to the presence of manganese, titanium, gallium), green (due to chromium), red (due to hematite), and yellow (due to ilmenite). There is a great deal of treated jadeite jade on the market, and much of it may not be properly disclosed.

Polymer-treated jadeite jade (known as ‘B’ jade) is first bleached to remove unwanted brown, yellow, and black stains and then polymer-impregnated to improve transparency. Structural damage occurs with this treatment, making the jadeite brittle. A chalky blue reaction under long-wave UV light is a good indication that jadeite has been polymer-impregnated, but the definitive test is infrared spectroscopy, which shows polymer peaks around 2900 cm -1 (wavenumbers).

Dyed jadeite jade is known as ‘C’ jade. It has additional amounts of chromium when dyed green, so the absorption band at 670 nm will be wide and strong, while natural-coloured jadeite has fine absorption lines of about 690 nm (Figure 7). The colour is unstable and fades under high heat and over time. The dye can be added to the polymer during the impregnation process, and the result is a chemically bleached, dyed, and polymer-impregnated jade (‘B+C’ jade). Dyed cracks may be visible with the use of a microscope (Figure 8, page 4). In addition, dyed jade fluoresces medium to strong greenish yellow, while natural-coloured jade usually does not exhibit any fluorescence.

Quality and valuation of jadeite and nephrite jade

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Colour, transparency, texture, and clarity are the most important elements affecting the value of jadeite jade (Figure 9, page 5).

1. Jadeite ranges in colour from white to black with intense greens, reds, and lavenders being the most sought-after. The least valuable colour is uneven black.
2. The higher the transparency and finer the texture, the more valuable the jade. Transparency is described using the following scale:
   • transparent (far right)
   • semi-transparent
   • translucent (middle)
   • semi-translucent
   • opaque (far left).
3. Texture refers to the internal characteristics of the jadeite, which is formed by a cluster of microscopic crystals. The smaller the crystals, the more valuable the specimen.
4. Clarity is based on freedom from cracks, common flaws like white, black, and brown spots, as well as grainy inclusions. The presence of different types of minerals results in black, brown, or white areas.

The evaluation of nephrite jade’s gem grade is based mainly on physical inspection of the following:

• a pleasing green colour (i.e. apple to emerald, although dark green is also used in some jewellery markets);
• good translucency (i.e. most jewellery-grade nephrite should be translucent to 4 to 5 mm in sunlight);
• good hardness (i.e. nephrite with a hardness of 6.6 to 6.8 on the Moh’s scale can achieve a higher polish that maintains its brilliance longer, as opposed to softer nephrite jade with a lower hardness of 6.3 to 6.5); and
• good clarity, namely, the lack of fractures and natural inclusions, such as black and green chromite spots and streaks.

Satisfying the masses

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Gem-quality Burmese jadeite is extremely rare and thus extremely expensive. Well-matched imperial colour (i.e. emerald green) jadeite beads have sold for more than $1 million US at Christie’s and Sotheby’s auction houses in Hong Kong, a major international jade market.

The availability and consistency of high-quality green nephrite has made this material an acceptable alternative to the more valuable Burmese jadeite.

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According to Makepeace, it would have been impossible to find green nephrite a few years ago in Guangzhou, China, the centre of the jade market. Today, however, hundreds of vendors can be found selling Canadian and Russian nephrite, mostly in the form of bangles ranging in price from $1000 to $10,000, as well as other jewellery and carvings. Makepeace says his retail outlet in Vancouver has seen its sales double in the past 12 months, with Chinese tourists buying product there for a fraction of what it would normally cost in China. Canadian nephrite jade can range in price from $10/kg for the lowest grades, which are suitable for industrial purposes like tiles, to over $1000/kg for the rarest gem-grade material.

Local artists transform the best B.C. nephrite into works of art, the most noteworthy perhaps being the Jade Buddha for Universal Peace unveiled in 2010 at the Dai Tong Lam Monastery in Vietnam. Viewed by millions of people around the world, the nephrite statue was carved from an 11,000-kg boulder and is valued conservatively at $5 million US (Figure 10).

Canada’s relatively small domestic consumption of four to five tonnes per year supplies a few successful jade artists of world renown. Awareness of the availability of Canadian jade has also led to non-traditional uses of this stone, with such notables as fireplaces in the Getty Mansion and translucent window panels in the Smithsonian.

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Pulling back the curtains on jade treatments and imitations

According to the Canadian Jewellers Association’s (CJA’s) guidelines, it is unethical to sell undisclosed treated gems. It is also improper to misrepresent a lower value gem as a more expensive one. Somewhere in the world right now, a retail jeweller may be offering Chinese dyed quartzite as authentic Canadian jade, which is factually and ethically wrong. This type of deception only serves to hurt legitimate Canadian jade dealers and also the consumer.

Fifteen years ago, improper disclosure of oiled emeralds caused a stir and impacted emerald prices. Ten years ago, beryllium-treated sapphires undermined this particular market, and five years ago, undisclosed lead glass-filled rubies surfaced and still continue to affect consumer confidence in coloured gemstones. A jeweller may read this article and think “It’s only jade,” but consider this: your gemstone products could be next. No gemstone is immune to tampering, making disclosure of the utmost importance.
 
The author would like to thank Kirk Makepeace of Jade West, Robert James of the World Gem Society (WGS), and Bill Vermeulen of the Canadian Gemological Laboratory (CGL) for their contribution to this article.

[13]Branko Deljanin, B.Sc., GG, FGA, DUG is head gemmologist and president of Canadian Gemological Laboratory (CGL) in Vancouver. He is a regular contributor to trade and gemmological magazines and has presented reports at a number of research conferences. Deljanin is an instructor of standard and advanced gemmology programs on diamonds and coloured stones in Canada and internationally. He can be reached at info@cglworld.ca[14].

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