I. Goods A (allowed): Wax dipping treatment
Emerald is an opaque to translucent gem. The emerald green we see is the result that part of the sunlight or white light is absorbed and reflected by jadeite. In order to meet the four requirements of color (strong), color (positive), color (positive) and color (uniform), jadeite must have a dense and smooth surface to reflect light like a mirror. However, jadeite is often mixed with other substances to form rocks, so its structure is not uniform. Observing under a magnifying glass, just like the skin of a shark, it is uneven and its reflection ability is greatly affected. Therefore, after finishing the polishing process, soak it with fruit acid, rinse the iron or other impurities on its surface slightly again (this process is called "yellow removal"), and soak it with wax liquid to make wax penetrate into cracks and pits to improve its reflective ability and luster. This practice has been implemented for many years and is generally accepted and allowed. It is called (a) jade or (a) jade in the jade industry.
2. Bleaching and polymer embossing jadeite is bleached and glued.
Bleaching and glue pouring of jadeite has become quite popular in jadeite market, especially in Taiwan Province Province, Hongkong and Japan. It is reported that 80-90% of high-grade goods have been processed. The method includes two main stages: the first stage is bleaching, also known as yellowing, that is, removing the jadeite boulder that has been cut into pieces or polished jadeite by chemical treatment (which may be caused by filling cracks with iron compounds). The second stage is injecting polymer (polymer impregnation) and even adding green pigment. The jadeite treated in these two stages is called bleached jadeite and polymer embossed jadeite in English, and its initials are (B), so it is abbreviated as (B) among jade merchants. So far, this treatment is limited to green or white jadeite, and no other jadeite such as purple to nephrite has been found.
(1) Bleaching and glue injection procedures
The first stage of bleaching: jadeite raw stone (wool), or jadeite raw stone that has been cut into plates or jadeite that has been polished, such as rings, pendants or bracelets. Soak with chemicals to remove brown iron compounds with cracks or granular structure. According to various sources, hydrochloric acid and fruit acid are the most commonly used bleaching agents, and other sodium compounds are also commonly used to bleach jadeite. Depending on the pollution degree or pollution source of jadeite, some jadeites only need to be soaked for several hours, while others need to be soaked for several weeks to be effective. After judging that the color has been improved to the greatest extent, take it out and rinse it with clear water. Of course, soda water is also used to "neutralize" the acid remaining on jade. So far, it is still normal operation. Many kinds of Rougth gems, such as emeralds, are treated in this way before polishing, and even corals are washed with dilute hydrochloric acid instead of polishing. This product is naturally unqualified because no other materials have been added.
The second stage: after bleaching, all or most of the brown spots between cracks or particles have been removed, but the white or pink-green texture is more obvious and unsightly. Bleached jadeite leaves pores due to decontamination, which makes it fragile. Even the bleached jadeite with the worst quality will be crushed by the finger back force. If you put it in jewelry without treatment for a long time, these pores will be filled with dirt and grease, which is even more unsightly. Therefore, the second stage operation must be carried out: polymer injection, sometimes only wax injection, but most of them are injected with resin to replace the removed substances. In order to fill the pores and solidify the loose jadeite, a technician injected dye and polymer (Ng 1990) together, and then removed the residual polymer after the perfusion was completed.
(2) Identification method:
By measuring the gem properties of bleached and glued jadeite, there is no significant difference in refractive index and spectrum (hand-held spectrometer), but there are significant differences in specific gravity, ultraviolet fluorescence reaction, hot needle reaction test and high magnification characteristics (appearance), which can be used to test bleached and glued jadeite products. Recently developed a new instrument infrared spectrometer for jewelry identification, which is expensive and requires high technology, but it is the most expensive.
(1) Drop a small drop of pure hydrochloric acid on the emerald and observe for a few minutes (about 1-20 minutes). There will be many beads of sweat around the drop. This reaction is the interaction between crystal particles of jadeite and small cracks, sub-pores and capillaries. When using the same method to test bleached jadeite injected with glue, there is no such phenomenon (small round sweat) because the glue fills the sub-pores. Note that in dry and hot places, especially in air-conditioned rooms, hydrochloric acid will evaporate before you see the reaction, so be sure to keep dripping hydrochloric acid.
(2) With the help of the reflected light of the microscope, it can be observed that the filler reaches the surface crack. Low-grade jade with poor luster may also find white spots on jade pieces; Due to negligence in handling; In the sample of polished surface, sometimes we can see the bubbles of filler or the polymer of cotton wool fiber gathered in the transparent glue, and occasionally we can see the glue residue in the carved shallow grooves, depressions and pits.
(3) ultraviolet fluorescence reaction
Most untreated natural jadeites do not respond to ultraviolet radiation. Under long-wave ultraviolet radiation, some of them are white with light to moderate yellow, but they are weak or unresponsive to short-wave ultraviolet radiation. The green part didn't respond. However, the bleached and glued jadeite has a fluorescent reaction to long-wave ultraviolet rays. However, under short-wave ultraviolet irradiation, the response is slow or unresponsive. Generally, it shows weak blue-white fluorescence under long-wave ultraviolet light, and sometimes it is more obvious in white places, which is roughly from the injected rubber.
Therefore, it shows blue-white to yellow-green fluorescence under long-wave ultraviolet, which provides a useful index for the bleaching of rubber-injected jadeite. However, this test must be carried out in a dark room. If it is in a bright place, you can't see the fluorescence, and the fluorescence reaction of the gem is mostly for reference, so it must be determined by other methods. Of course, there are many high-grade B goods now, and this issue may be invalid.
(4) knocking at the door:
Distinguishing the quality and grade of jadeite, as the old saying goes, the six-character formula: color, transparency, uniformity, shape, knock and photo, has always been the motto of the jade industry, among which "knock" is more useful in identifying B goods. Large items, such as jade bracelets, are tapped with coins. If it is natural and untreated high-grade goods, it will make a crisp and pleasant sound, while B goods will make a gloomy and depressing sound. Its theoretical basis is that the rubber compound or crack in the jadeite structure blocks the sound wave, while the untreated sound wave vibration is not hindered.
(5) infrared spectrometer:
Infrared spectrometer is only available in research or academic institutions, which is expensive and difficult to operate, and is commonly found in jewelry appraisal laboratories. But it is the most accurate to identify whether jadeite has been treated with glue injection. Using this instrument, we can find that there is a strong absorption peak at about 2900cm- 1 in the infrared region. In addition, the glue (polymer) used is mainly wax, phthalate and opticon. Among them, the most commonly used resin is 224.
Third, the coating treatment of C goods (coated jade)
The method of coating treatment is to coat a thin green film on the surface of white inferior jade (which can be replaced by other decorative stones such as Indian jade), so that the original colorless white jade becomes green and transparent "crown green". In fact, several kinds of gems have been coated to improve their colors. For example, faceted natural emeralds are covered with a layer of green substance to impersonate emeralds (Kane1982); Colorless jadeite beads covered with red substances; Starlight colorless sapphire covered with plastic posing as Xing Cai Hongbao, etc.
This jadeite with a coating on its surface does not react under the color filter and ultraviolet light. The general identification method is to examine its characteristics by magnifying with a microscope: (1) The surface has lost the rough surface (pits and depressions) unique to jadeite; Because it is wrapped by plastic film, it is smooth. (2) It can be seen that the dyeing color of the adhesive film is in the form of tiny dots, which are scattered on the joint surface of the adhesive film and the seed jade. Especially the blue table at the bottom is the clearest. (3) Turn the jade upside down. When you turn it upside down, you can see that the color is concentrated around the jade. (4) Sometimes you can see that the damaged part of the film shows the original color of jade (as shown in Figure 6). You can also puncture the adhesive film with a hot needle or pin, but this method must be used with caution. In addition, the spectrometer can observe a thick absorption spectrum in the red region.
Four. Dyeing treatment of goods D (jade dyeing)
At present, dyed jadeite is called (c) "colored jadeite". In fact, the word "dye" in jewelry literature is used for artificial dyeing, and "coloring" refers to natural coloring. At that time, I didn't know if I had been painting jade. Now it is called "C" because dyed jadeite is hard planted as colored jadeite. Look at you. Although jadeite can be dyed in various colors, it is generally dyed green and purple, especially green. Not only bare stones and jadeite can be dyed, but also sliced and raw stones (raw materials) can be dyed. The dyeing process includes two steps: heating and applying high pressure. Heating must be done carefully and slowly to promote the opening of the pores of jadeite, and then the dyeing diffusion penetrates the entire jadeite surface under high pressure.
The early dyeing was only used to finish the polished bare stone, and it was done in secret behind closed doors. No one admitted to dyeing. This local dyeing takes a long time and often needs to be repeated 6 to 12 times to get good results. First of all, jadeite must be heated slowly, which requires training skills and experience, otherwise heating too fast will easily lead to cracking. So you can't directly heat jadeite. Just like frying chestnuts, put jadeite in a pot filled with iron ore (pebbles for frying chestnuts) and heat it indirectly for 5- 15 minutes, then put it into the dyeing solution to immerse the dye in the cracks, main veins and capillaries to achieve the purpose of dyeing. Now scientific and technological progress is based on large-scale dyeing. Iron ore is no longer used for heating, but instead of modern equipment such as ovens and pressure cookers.
Characteristics of dyed jadeite:
The real fine dye is unrecognizable to the layman's naked eye. There must be experts to test in a scientific way, plus professional knowledge to identify. For products with rough dyeing, the following characteristics can be observed by naked eyes:
1. The appearance color is dark, dull and blue, because it is stained with blue pigment.
2. Color only exists in the surface layer and looks' floating'.
3. The distribution of color is divided into veinlets by dyed main veinlets, just as the main roots of plants are divided into lateral roots, which are all over the stone.
4. The dyed jadeite will lose its luster and become "dry" or "water-deficient" (opaque).
5. Blue is unnatural and called evil color.
6. The color is particularly "neat", just like wearing a uniform.
7. Although dyed jadeites are mostly monochromatic, it does not mean that multicolored jadeites will not be dyed. In particular, bracelets are more likely to be dyed into green, purple and red bracelets, which are called jade bracelets, land bracelets and longevity bracelets.
Check with standard gem identification instrument;
1. People dyed green are orange or pink under the Charles filter; Blue pigment and root lines can be observed under the microscope; Observing with a hand-held spectrometer, it can be found that there is a wide and fuzzy absorption band from 6300 A to 6700 A.
2. Those dyed purple have a strong to strong orange fluorescence reaction under long-wave ultraviolet light and a weak orange fluorescence reaction under short-wave ultraviolet light.
3. Dyes (pigments) gather in cracks on the surface.
Emerald certificate
Recently, it has been found that the appraisal certificates provided by jade jewelry merchants in many places are issued by consulting institutions that do not have appraisal qualifications and legal effect, which is very deceptive to consumers! Because at present, many of these so-called "appraisal institutions" do not have professional gem appraisal instruments, and only rely on naked eye observation to determine accessories for inspection. The appraisal result is extremely inaccurate!
Not to mention! ! ! Provide forged appraisal certificate! ! ! According to reliable sources, as for the appraisal certificate of nephrite, you only need to spend 50 yuan in Xinjiang to buy an appraisal certificate that writes the appraisal results of Qinghai white jade and Russian white jade as "suet white jade"! ! ! Anyone who knows a little about trade knows it. According to the national standard, the appraisal results only say: nephrite chromaticity: fat white, gray white, white and bluish white. Scrawled: "Hetian jade" or "white jade with sheep fat". Isn't this a joke on the world?
Another reason is that some unscrupulous profiteers cheat consumers by taking advantage of the weakness that some buyers are unwilling to spend money to re-identify their identities after buying jade ornaments with low value! (Most people will consider buying a small thing for only two or three hundred yuan, but it will cost about one hundred yuan for another appraisal. Isn't it still expensive! Anyway, the seller has provided the appraisal certificate, so it's not necessary to spend money and trouble. There are really not a few buyers who consider this. The result is often recruited! ! !
So advise everyone that the certification certificate must be clearly recognized! Even if it is a commodity with low value, it should go to the local authoritative appraisal department for re-appraisal after purchase. For consumers who do not have an authoritative appraisal institution in the local area, the seller should also be required to provide the certificate of the local authoritative appraisal institution, even if he bears the appraisal fee.
The following will introduce the key parts of the legally effective appraisal certificate recognized by the state.
First of all, look for the capital "C MA" sign, pay attention! "MA" is a capital "c"
Secondly, the appraiser's signature on the back of the certificate must be signed by two different people. One copy is signed by the appraiser and the other by the inspector.
In addition, if the identification result is jade A, the results are printed: jade carving, jade pendant, jade bracelet and jade inlay; If the appraisal result is not A, print the appraisal result: "Optimize Emerald ××". Special reminder to everyone! ! ! !
There are also three kinds of A goods.
There are actually three kinds of commodity A, and the new national standard has classified the third kind as treatment, namely: jade (treatment):
There are five kinds of jade ornaments, one is natural, the other is optimized (bleached and waxed), and the other is treated (filled with polymer after bleaching and dyeing). What I want to mention here is the word "treatment", which is often equivalent to the meaning of processed products in people's consciousness. Actually, it is not. Treatment is only an improvement on the development and utilization of jadeite, a natural non-renewable resource.
1, natural jade ornaments
Refers to the raw materials after mechanical cutting, rough grinding, fine grinding, fine grinding, polishing and other technological processes. Bracelets, pendants, beads, rings and other high-grade jade ornaments. It is made by physical and mechanical processing. The column of national standard test conclusion is called "jade", which is commonly known as "A goods" among the people.
Step 2 bleach jade ornaments
It is a chemical treatment method, which aims to dissolve the disharmonious impurities (minerals) on the surface of jade ornaments, and its dissolution is limited to the surface, making the surface of jade ornaments more pure and beautiful. Bleaching is a traditional process. The column of national standard test conclusion is called "jade", which is commonly known as "A goods" among the people.
3. Bleached and waxed jade jewelry
It can be regarded as a wax filling effect on the surface and surface microcracks of jade ornaments. Wax dipping can increase the smoothness of jadeite jewelry surface and partially fill the rough surface formed during processing, especially the corners of some carvings. Wax dipping can cover up the primary and secondary microcracks on the surface of jade ornaments, making jade ornaments look more pleasing to the eye. It is a traditional process, and the column of national standard test conclusion is named "jade".
In fact, we think that only the first kind is goods A, the second kind is called A+B, and the third kind is called pier wax. Pier wax is a widely used process in bracelet processing, and good A goods are not pier wax.
Everyone should pay attention to such problems when buying. Some products may actually be A+B products even if goods A are marked on the certificate.