HomeJadeite Types and Treatments
Jadeite Types and Treatments
 
 
The treatment of jadeite in an effort to enhance its value has a long history, but it has become an especially widespread phenomenon in recent years. With the appearance of jadeite that had been bleached and then impregnated with polymer on the market in the 1980s it became common practice to classify jadeite according to the presence and type of treatment. At first there were three categories—"A", "B" and "C" (see Fritsch, et al 1992, Mok 1999: 10). More recently a fourth category, "D", has been added. The "A" category essentially refers to untreated jadeite. After the surface of cut jadeite is polished it is often waxed with beeswax to fill surface pores. This is a long-standing practice and is not considered to detract from the value of the stone. Treated forms of jadeite are categorized as "B" jade, "C" jade, and "D" jade respectively.

It should be noted that the types of treatment discussed here are associated with Burmese jadeite. In the case of Guatemalan jadeite, for example, Miller (2001: 29) states that "no heat treatments or other enhancements are used in Guatemalan jadeite."

A Jade. So-called "A" jade is commonly dipped in wax to improve its luster and fill surface fractures and pits. Virtually all jadeite undergoes this process after being cut and polished. The first step of the process is to soak the stone in a warm alkaline solution for five to ten minutes in order to remove the residue remaining after polishing. The stone is removed from the solution and rinsed and dried. Next it is soaked in an acidic solution known as "plum sauce" to remove residue from the alkaline solution. Once again, it is removed and rinsed and dried. Then it is placed in boiling water for several minutes. This is said to "open the pores" of the stone and serves to bring it to the right temperature so that it will not crack when placed in the wax solution. Now the stone is ready to be placed in a solution of melted wax for anywhere from a few minutes up to several hours. After it is removed from the melted wax and allowed to cool, the stone is polished with a cloth.

C Jade. Let us turn next to the so-called "C" jade since the type of treatment associated with this type of jadeite has been around for a while. This category refers to jadeite that has been stained or dyed. Wu (1997), Ehrmann (1958), Ng and Root (1984), and Ho (1996) are among the authors who have discussed and described this method of treating jadeite in Hong Kong. Staining white stones green (particularly to an imperial jade color) or lavender is the most common practice, but stones are sometimes stained red or yellow as well. Wu (1997) notes that staining pale colored material with vegetable or other organic dyes to produce green, lavender, and orange-brown jadeite has been done in Hong Kong since at least the 1950s. Ehrmann (1958: 134-135) provides a description of the process as shown to him by one of its practitioners in Hong Kong:



He arrived with all kinds of paraphernalia, including a small charcoal burner, various shaped bottles, tweezers, towels, wax, and a grate... The method was extremely simple. The stones had been cut encabochon from fine-quality, translucent, whitish-gray material. He heated them on a grate on top of the charcoal burner until they turned to a glossy, opaque finish. He then cooled them for about a minute and then placed them into a prepared dye solution for a short time. (Under normal circumstances, the stones are left in this dye solution for forty-eight hours.) After removal from the solution, they were rinsed in alcohol, dried on a towel and put aside. in the meantime he had heated paraffin wax very slowly in a double boiler. The stones were placed in the melting wax until they were completely covered, then removed and wiped carefully. The basic coloring dye was an acid-base dye-stuff, such as is used in dyeing cloth. In this case, he used a yellow dye and a blue dye.



Not only is jadeite dyed to increase its value, but jadeite simulants are also dyed to imitate jadeite. This appears to be a very old practice and it is likely that the practice of dyeing jadeite itself is probably far older than the 1950s as well. Goette, in his 1937 classic Jade Lore (reprinted in 1976), provides a brief discussion about dyeing (page 118): "Sometimes soapstone and other white substances are dyed in browns and greens in imitation of either nephrite or jadeite" and that "specimens of white stone" are also "dyed a sickly pink." He notes, however, that "in such cases, the detection is comparatively simple, for the coloring is streaked, and apt to be darker along the veins of the stone" and, in the case of those stones dyed pink, that "no one could possibly mistake them for jade, but if they should be, certainly the buyer has little cause to complain of the vendor's dishonesty." It is apparent from Goette's discussion that the quality of dyeing has improved considerably in recent decades.

Webster (1975: 233) states that while "green-stained jadeite is prone to fade," lavender-stained jadeite does not appear to fade. Hughes, Galibert, et al (2000: 23), however, report that they "have seen fading in both dyed green and dyed lavender jades, but the green dyes tend to fade more readily."

Read (1999: 161) states that "most dyes can be removed with the aid of a cotton swab moistened with a solvent such as acetone." Staining can be detected through magnification as well through tests with a Chelsea filter, spectroscope, or long-wave ultraviolet light. In regard to magnification, staining is usually concentrated along grain boundaries or surface cracks rather than throughout the stone. When examined through a Chelsea filter, un-dyed jadeite will not show the red color that appears in the case of dyed jadeite (or nephrite). Read (1999: 160) reports that a spectroscope test "will usually show a tell-tale broad absorption band in the red due to the dye, and an absence of typical chromium lines in the same part of the spectrum" in the case of stained green jadeite. Mok (1999: 12) describes some material dyed green thus: "green jadeite dyed with chromium salts will show a broad fuzzy band in the red." He says (1999: 160-161) that "dyed mauve jadeite may exhibit a bright orange fluorescence under long-wave ultraviolet." Hobbs (1982) writes that a broad band from about 630 to 670 nm in the red region of the visible spectrum is considered proof of dye in green jadeite. Some of the newer dyes may also show a weaker band at 600 nm. Since stones may be only partially dyed, the entire piece should be checked. Koivula (1982) discusses jadeite that has been dyed lavender, noting that such jadeite shows orange under long-wave ultra-violet light. Field (2000: 3) remarks that "anything but a pale shade [of lavender] is immediately suspect." Webster (1975: 233) describes such stones as having a color that is "too pronounced" and that the "stones look unreal."

B and D Jade. The categories "B" and "D" jade refer to jadeite that has been bleached and then impregnated with polymer. Mason-Kay Fine Jade Jewelry refers to "B" jade as "the bad stuff" and "D" jade as "the worst stuff of all" (www.masonkay.com/whatisbjade, pg. 1). Don Kay, of Mason-Kay, is quoted as stating that "the majority of jade pieces seen on the market today are "B" jades" (Miller 1999: 91). Fritsch, et al (1992: 178) report that one of the authors of the article "saw this type of treated jadeite as early as 1984." However, widespread public knowledge of this problem did not emerge until around 1988. Writing only a few years later, Fritsch, et al (1992: 178) mention that "today, significant amounts of jadeite treated in this fashion are believed to have entered the market via treatment facilities in Hong Kong and Taiwan" and comment that "in the experience of one of the authors..., as much as 90% of the jadeite sold in Taiwan has been treated in this fashion' dealers report that large amounts of this material are being sold in Hong Kong as well."

So-called "B" jade is made from jadeite that is blemished with internal stains. Basically, this is jadeite that if left untreated would be worth relatively little. Fritsch, et al (1992: 176) report that apparently only green and white jadeite are treated in this manner. The stone is immersed in a powerful acid (e.g., sulfuric or hydrochloric acid). The acid may be heated to increase its strength. The stone can be immersed more than once over a period of several weeks. The acid immersion leaches the sodium out of the stone and in the process removes the stains. Mason-Kay comments that "at this point, it could be said, one no longer has jadeite jade at all." The stone is then placed in a neutralizing agent. Then it is injected with a polymer with the use of a centrifuge. This process serves to completely cover the stone in a hard and clear plastic-like coating.

Fritsch, et al (1992: 178-180) provide a relatively detailed description of the treatment, but do not positively identify the ploymers used. Using Fourier transform infrared transmission and x-ray photoelectron spectroscopy, Quek and Tan (1998) identify the polymer as polystyrene. The authors comment (1998: 171) that polystyrene has several properties that make it suitable for impregnation: "it is hard, cheap, readily available, has low moisture absorption, is easy to fabricate and has surface smoothness and clearness." Moreover, they note that not only is polystyrene easy to use for this purpose, but "detection is extremely difficult, especially when only small amounts of the polymer are used."

Beyond the matter of fraud, there are problems with the durability of "B" jade. Mason-Kay reports (www.masonkay.com/whatisbjade, pages 1-2):



Current research indicated that 'B' jade will, in time, become unstable and will discolor. We already know that it is not nearly as durable as natural jade, and that ordinary household detergents can break down the polymer. Whereas real jade is often cleaned with acetone..., 'B' jade completely clouds up when acetone is applied. There are reports of 'acid leak' from improperly neutralized stones (skin burns are the result). Heavy prongs or bezels can actually penetrate the weakened surface of the treated stone.



Quek and Tan (1998: 171) note that polystyrene that is used for impregation "degrades under ultra-violet light" and that "this could be the reason why some treated jadeites turn dark and have a greyish colour after some time."

Understandably, there is considerable interest in the identification of "B" jade. In her discussion of the problems facing appraisers confronted with the "B" jade problem, Anna Miller (1999: 91) remarks that identifying such jade "is destined to become the big buying and selling issue of the next decade." Fritsch, et al (1992: 181-182) tested jadeite for treatment by means of specific gravity. The bleached stones that they tested initially had a lower specific gravity (3.22 to 3.25) than untreated stones (about 3.32). However, some jadeites are lighter due to an admixture of amphiboles or feldspars and, moreover, later they encountered bleached stones that exhibited less difference when tested in this manner. As a result of these findings, they warn that "specific gravity provides a generally useful indication, but not proof, of 'bleaching treatment." Fritsch, et al (1992: 182) also tested by means of ultraviolet luminescence and found that "a bluish white to yellowish green luminescence to long-wave U.V. radiation provides a useful indication of treatment," but warn that "the reaction is sometimes faint and can easily be missed." For this and other reasons, they conclude that "this identification criterion alone cannot be considered conclusive."

"The only definitive test" that Fritsch, et al (1992: 186) found was infrared spectroscopy using a Fourier-Transform Infrared Spectroscope (otherwise known as FT-IR or Fourier Transform Infra-Red). The presence of a very intense group of peaks around 2900 cm-1 and accompanying features in the mid- and near-infrared regions is characteristic of polymer impregnation. Mok (1999: 12) notes that "because resin is [a] hydrocarbon organic substance, it will display a diagnostic spectrum under the FTIR test." Using a Fourier-Transform Infrared Spectroscope with a near-IR fiber-optic probe accessory, Gao and Zhang (1999: 306) found that this was "an effective and easy method for testing jade in various kinds of jewellery, and is particularly applicable to large samples." Unfortunately, such equipment is expensive. Miller (1999: 90-91) reports that at the time of her writing there were only two such units available for testing jadeite in North America: one owned by the GIA and the other by Mason-Kay. In Asia, she noted that the Far East Gemological Laboratory in Singapore had a unit and that several laboratories in Hong Kong had one. Mason-Kay obtained its FT-IR in 1995 and, as of early 2001, remained the only commercial firm in North America with such technology for jadeite testing.

Despite such assurances and the widespread acceptance of FT-IR testing, there are problems associated with it and there are also other possible ways of testing for treated jadeite. Tan, et al (1995: 475) note that "the identification of treated jadeite using infrared spectrocopy is severely limited by its response in only certain parts of the mid- and near-infrared frequency ranges and by the restriction of this measurement to specimens of thin jadeite [no more than 12 mm thick according to Quek and Tan (1997: 417)] which is not opaque to infrared transmisions." Additional problems are that FT-IR "may not be able to detect impregnation materials other than wax and polymers (Tan, et al 1995: 482) and it cannot be used if the stone is "already a part of a piece of closed-setting jewellery" (Quek and Tan 1997: 417). Tay Thye Sun, S. Paul, and C.M. Puah (1993) report that polymer-impregnation can also be tested by using a Scanning Electron Microscope to examine the damaged grain boundaries. However, this equipment is even rarer and more expensive to use than the Fourier-Transform Infrared Spectroscope and its findings are not unambiguous.

Tan, et al (1995) 475) sought to overcome the above diagnostic limitations by using X-ray photoelectron spectroscopy (XPS), which they note (page 479) "has been shown to be a useful tool for studies of chemical compositions of polymers." With a sample of sixteen stones that included four rough pieces, five natural untreated polished stones, and seven stones that had been treated, the authors found XPS to be "a useful non-destructive technique distinguishing unambiguously bleached impregnated jadeites (B-jade) from the natural and untreated ones" (page 475). Furthermore, they note that "this non-desctructive technique has been found to be capable of determining the chemical composition of the surface of jadeite and thus can identify foreign elements present" (page 482). Once again, however, the equipment for this test is rare and expensive: "its use is severely restricted to research laboratories as the apparatus is expensive and eleborate expertise is required" (Quek and Tan 1997: 410).

Noting that the technique had been used previously in gemmology for other purposes, Quek and Tan (1997) used diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy to test for B jade. The equipment used in the test included a PerkinElmer System 2000 FT-IR spectrophotometer with a fast recovery deuterated triglycerine sulphate detector and a Harrick Diffuse Reflectance Attachment (HDRA) (see pages 420-421). The authors used a sample of three wax-buffed stones, three bleached wax-impregnated stones, and four bleached polymer-impregated stones. The samples were also tested using the XPS technique. With the XPS test, Quek and Tan (1997: 420) found that it was "difficult to distinguish a wax-buffed jadeite from that which is wax-impregnated." The DRIFT test proved useful in "differentiating a natural (wax-buffed) jadeite from one which is treated, and from one which is wax-impregnated from one which is polymer-impregnated" (Quek and Tan 1997: 426). The authors point to a number of advantages to using the DRIFT technique:

It is a relatively inexpensive and yet accurate way of differentiating natural and untreated jadeite from bleached wax- and polymer-impregnated jadeites. Also, since only the surface of the jadeite sample is tested, the thickness of the jad esample or whether it is part of a piece of jewellery is not of any consequence... In addition, the sensitivity of the DRIFT technique allows the reliable identification of the chemical composition of the surface coating of the jadeite sample.

Emphasis should be placed on the word "relatively" since this test is relatively inexpensive only when compared to the other tests discussed above and still does not allow for a truly inexpensive test available to most gemologists.

Mention should also be made of the practice of treating jadeite in order to make it appear older (i.e., to make new pieces appear to be antique). Hu (1976: xi) describes a long-standing Chinese practice: "Various acids were used to color jade, and new pieces were often buried in quicklime with dead animals for several years. This process changes their color so that imitations can hardly be detected from genuine ancient pieces." This is more of an issue with purported antique nephrite pieces, but indicates that care should be taken with supposedly older jadeite pieces as well.

翡翠A B C货详解与区别
翡翠的A货,为纯天然翡翠,只经过雕刻打磨。
翡翠的B货, 国家颁布的珠宝玉石标准,优化翡翠为加工过程中,经过了酸浸漂白,墩蜡处理的翡翠。根据酸浸漂白的强弱,还可分为强腐蚀与弱蚀腐两种,强腐蚀优化翡翠相当 于市场所称无胶B货。其内部己受到很大程度的破坏。充胶处理翡翠在加工过程中,经过了强酸腐蚀漂白、去劣存优处理,其翡翠内部结构受到严重破坏,然后注入 增透固结的胶质聚合物填补称充胶货。不管优化翡翠还是充胶处理翡翠,实际上应定为破坏性处理翡翠即B货。而弱腐蚀翡翠,因对其内破坏性不大,应称优化翡 翠。充胶加色处理翡翠及无胶力日色处理翡翠,通过酸浸漂白注胶或不注胶,并加入染色剂的翡翠饰品称B+C货。
翡翠的C货, 为染色翡翠。不管酸浸漂白与否,充胶与否,凡人工加色的翡翠称C货。目前翡翠处理的新动向,强酸处理后,不充胶,而是充蜡。充蜡为优化,充胶为处理(B 货),故钻了国家法律的空子。另外,很早就有用水玻璃(硅质物)充填翡翠,效果很好,目前尚无人知晓。还有用纳米级的铝质物、硅质物充填翡翠的,均称为高 级B货。
翡翠BC货和A货的最大区别就是:它们的本身结构已经被破坏了。因此翡翠BC货就有与A货不同的内部及外部(也是基于内部特征的外在表现)特征,具体说起 来呢,BC货首先都是经过酸洗,其内部结构被破坏,有一些矿物质(主要是杂质)被酸带出,这样透明度通常会提高,而原来的裂隙扩大,因此其结构就不如A货 致密,从物理和化学性质来说,其密度、折射率、硬度等性质就会相应有一些变化,但因为这种变化比较微小,因而不容易测出。然后B货会经过充胶处理,胶会充 填到裂隙中,因此仔细观察裂隙会有胶的痕迹;而C货经过染色处理,因此其颜色是人工充填进去的,看上去和翡翠天然形成的颜色就不同,行货说色比较“邪”就 是这个意思。另外,上面已经提到经过处理的翡翠硬度有所变化,具体地说是降低了,所以在抛光的时候就不可能抛出象A货那样的油脂光泽,而且因为结构被破 坏,抛光的时候其表面一下矿物可以就会被抛掉,形成一个个的小坑点,并且形成象橘皮一样的纹路,就是所谓“橘皮纹”。

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