Corundum ruby (blue) is a common high-grade gem in the market. The optimization of this kind of GEM has a long history, various types and continuous innovation, mainly including the following:

1. heat treatment method

Ruby (blue) is the most widely used gemstone in heat treatment, and most of the rubies (blue) on the market are this optimized gemstone. People artificially treat natural ruby (blue) through various heat treatments to improve color and transparency. At present, sapphire containing iron ions can be changed from colorless, light yellow-green to yellow or orange; Improve that sapphire containing iron and titanium ion from colorless, light blue or blue-black to sapphire blue; Raise ruby from cow blood red to chicken blood red, that is, eliminate the purple or blue tone of ruby. In addition, people can also eliminate rutile and other inclusions in red (blue) gems by heat treatment, and increase the transparency of gems. Or conversely, the needle-like inclusions in the gem can be increased to make the gem produce starlight. This method of improving and optimizing the color or transparency of gemstones generally does not require identification, nor does it need to be declared when selling. The industry does not consider it fraud.

2. Diffusion treatment method

This method is to diffuse a thin layer of color on the surface of the gemstone through high temperature treatment, and the thickness of the color varies from 0.15 ~ 0.42 mm. The general raw material is natural colorless or light-colored corundum. Recently, it has been found that synthesizing corundum gemstones is useful. The diffuse colors are blue, red and orange, and some diffuse starlight on the surface of gems. Diffused gemstones have attracted wide attention in the jewelry industry all over the world. People are not allowed to sell this gem directly as a natural gem, and it must be declared that it has been diffused when selling.

The identification basis of diffusion-treated gemstones is that the original stone is colorless or light-colored natural corundum, and its color is artificially diffused into the crystal at high temperature, and the color is limited to the surface layer of the gemstone, while the core part of the gemstone is still shallow or colorless original natural corundum, and the color layer of the gemstone can be partially or completely removed by cutting or polishing.

The effective way to identify sapphire treated by diffusion is to immerse sapphire in oil and enlarge it, and observe it with naked eye or microscope. The characteristics of high temperature are as follows: (1) the surface of sample blank is sintered; The diffusion layer can be seen by magnifying observation; Concentrated dark and diffuse pigments are often deposited in the surface cracks or surrounding pores of gems; Inclusions in gems are often melted around, or rutile "filaments" are melted into dots or adsorbed. Because the color is limited to the surface of the gem, the characteristics observed under oil immersion are as follows: (1) deep color lines or high protrusions appear obviously at the facet joints and waistlines; The whole gem looks uneven in color, with some deep facets and some shallow facets, which are called point facets, which are the result of uneven thickness of diffusion layer and re-polishing after diffusion. It is often completely colorless at the waistline, and the whole waistline is clearly visible, which is called the waistline edge effect; In diiodomethane, facet joints are clearly visible, with a clear blue outline on the whole, while natural gemstones can't see the facet boundary, and the overall edge is not clear.

Diffusion-treated corundum, sapphire and ruby first appeared in the market. Since 2 1 century, an orange-red diffusion-treated corundum has appeared in the market. It has been studied that its color is artificially infiltrated with beryllium. Used to imitate the expensive natural orange-red papaya corundum gem.

3. Other methods

Because people's demand for rubies and sapphires is eternal, and the output of natural high-quality corundum gems is limited, almost all methods of optimizing gems are used to improve rubies and sapphires, such as dyeing, oiling, plastic filling and so on.

Second, topaz and its improvement method

Topaz (mineral name topaz) is one of the common gems and is essential for jewelry stores. The color of topaz gemstone is related to the content ratio of F and OH in its chemical composition. Topaz in pegmatite has a low OH content, and F is close to the theoretical value, which is called F- topaz, usually colorless or brown. The OH content of topaz in other occurrences, such as greisen, increases to 5% ~ 7%, and the F and OH content of topaz in vein rocks of hydrothermal origin can be almost equal, called OH topaz, which is often yellow or pink. There is also an orange-red topaz, which is a very precious variety.

1. Discoloration

The discoloration of topaz can be achieved by radioactive irradiation and heat treatment.

(1)F topaz: colorless or brown variety, which turns dark brown or greenish brown after irradiation. After heat treatment at about 200℃, beautiful blue topaz with different shades can be obtained, some of which look like aquamarine, but they will lose their color and return to their original state after excessive heating.

(2)OH topaz: colorless or light yellow variety, which can turn into orange red or orange yellow after irradiation and recover color after heating. Pink or purple varieties containing chromium can become orange-red and red after irradiation, and can recover their original colors after heating. There is also a kind of cyan topaz produced in Brazil, which is dark brown after radioactive irradiation and can turn pink after controlled heat treatment. After proper irradiation, it can appear golden yellow, but it will not turn blue.

2. Irradiation technology

All devices that can produce radioactivity can be used as "sources" to irradiate topaz. At the earliest, people put radioactive substance radium in a test tube and mixed it with precious stones, and put it in a lead box to irradiate precious stones. The equipment commonly used by modern people are cobalt 60, high and low energy electron accelerator, reactor and so on. These devices have their own advantages and disadvantages.

Cobalt -60 can produce γ-rays, which are uncharged, penetrating and evenly irradiated. Type F topaz turns brown in different shades after γ -ray irradiation, and the general irradiation dose is 109 ~ 10 10 rad. Light blue topaz can be obtained after heat treatment. Gems irradiated by γ -rays have no radioactive residue, but they are light in color and have little application prospect.

The high-energy electrons produced by the electron accelerator have much higher energy than gamma rays, shorter irradiation time, less radioactive residue and bright colors. After heat treatment, the color of topaz is very similar to aquamarine. Accelerator is a common equipment for irradiating topaz, but its use is limited because of its huge equipment and high cost.

A nuclear reactor is a device that generates huge atomic energy through nuclear fission. Many kinds of neutrons can be produced in the reactor, including fast neutrons, slow neutrons and thermal neutrons. Among them, the radioactive residue of fast neutrons on gemstones is very small. Therefore, when irradiating gems, people try to filter out other neutrons and try to let only fast neutrons pass through. The neutron irradiation efficiency of topaz is very high, and the dark topaz can be obtained quickly, and the blue finished product can be obtained after treatment. Because the reactor has many channels and large volume, the amount of samples irradiated at one time can be very large. The biggest feature of neutron irradiation in reactor is that the sample contains some radioactive residues. In order to ensure personal safety, it needs to be placed for a long time, and the radioactivity can only be put on the market if it falls below the national allowable standard.

3. Heat treatment

Heat treatment is the reaction of irradiation treatment, and the color center produced by irradiation is the reason why the color of gemstones becomes lighter. Some of these color centers are stable and some are unstable. The purpose of heat treatment is to remove the unstable color center with bad color and leave a beautiful color center with good stability. When heated to 180 ~ 300℃, the brown and brown centers in topaz can be eliminated and the blue centers can be exposed. A comprehensive treatment method can obtain blue topaz with ideal color, which is usually irradiated by reactor and accelerator, and then heat treated.

4. Detect the changing topaz

The color of topaz is mainly formed by color center, and the key to the formation of color center is the stability of color center. Generally, the residual color centers after heat treatment can be considered as stable color centers. For example, F-type blue topaz, its irradiated products are consistent with natural products in appearance and color mechanism, and both are blue color centers formed by external irradiation. The only difference is that the irradiation product is the product of artificial large dose and short time irradiation heating; Natural products are the result of small dose, long-term irradiation and light in nature, so it is difficult to distinguish these two kinds of blue topaz. Recently, it has been suggested that the luminous intensity of natural blue topaz suddenly increases at 350℃, while the luminous intensity of artificially irradiated products can increase below 300℃. This method often destroys the color of gems in detection, which is of little practical significance. At present, there is no nondestructive method to accurately detect whether the color of topaz has been irradiated.

However, it is necessary to detect the radioactivity of irradiated topaz, generally using gamma meter. Some foreign businessmen often put a small gamma meter on the counter to detect the radioactivity of gems in front of customers. It is generally considered that it is safe to read less than 50 micro roentgen/hour (the background value is 20 micro roentgen/hour) on the gamma meter.

In addition, a tan-orange topaz can also be pink, and a pink gem with stable color can be obtained by heat treatment at a relatively low temperature. It is reported that this heat-treated topaz has stronger dichroism than natural pink topaz.

Third, the best treatment and identification of diamonds.

The artificial coloring of diamonds is mainly accomplished by heat treatment after irradiation. First, diamonds are irradiated by radioactive sources. At present, most of them are irradiated by electron accelerators into blue, green, blue-green and brown. Then, according to the need, it is heat-treated to red, purple, blue and other colors. The identification of irradiated colored diamond is a difficult problem in jewelry industry, which has not been well solved so far. At present, only by looking for the difference of spectral characteristics, we can see the difference of absorption such as spectrum and infrared spectrum, but due to many influencing factors, the accuracy is still lacking. Blue diamonds have different characteristics. Natural blue diamonds contain boron, which is essentially a semiconductor and can conduct electricity. The irradiated blue diamond is an electrical insulator and does not conduct electricity.

In recent years, there is also a kind of diamond that has been artificially treated by warm pressing to remove the variegated color and become white. The insiders believe that this method is mainly used for structural defects caused by yellow or brown IIA diamonds. At present, according to the industry agreement, diamonds treated by this method must be sent to GIA in the United States for classification, and the waist edge is marked with "Ge pol" by laser.

For some diamonds with characteristic defects, people often adopt some treatment techniques, which usually do not improve the purity level of diamonds, but only change the appearance of diamonds and make them easy to sell. In the trade rules of the industry, it is clearly required that diamonds treated by this technology must be declared.

"Laser drilling" technology, aiming at the diamond with obvious dark inclusions, uses the laser beam to burn a tiny channel from the diamond surface to the inclusions, with a drilling diameter of 0.002~0.02mm and unlimited depth. This technology is to fix the diamond on a fixture that can rotate accurately, and adjust the laser with the help of a microscope, so that the laser beam reaches the dark inclusions on the diamond surface vertically, so that the inclusions will evaporate. In order to clean pores and bleach the residue of inclusions, further treatment is usually carried out with acid to make inclusions shallow. The channel is usually blocked by epoxy resin in vacuum, so it will be difficult to see when the diamond table is fixed on the jewelry. But it is easy to see from the side of the pavilion with a magnifying glass of 10 times.

Since 1987, the "crack filling" technology appeared in the market, which uses materials with similar refractive index to fill the open cracks of diamonds. This is consistent with the principle that jadeite "hides without breaking". Emerald inflatable cracks are easy to see, but oil with similar refractive index to emerald is often used to fill the cracks in the market, which is difficult to see with naked eyes. Filling can only improve the appearance of a gem, but it can't increase its value. Diamond crack filling is to inject a glassy material with high refractive index into the open crack of diamond in vacuum. The composition of the injected material has not been disclosed. The diamond treated by this method is easy to find large cracks, but it is difficult to find small cracks. The detection is mainly observed under a microscope, and the filling part can present a special orange or blue-purple flash with the movement of the diamond, and the flash is often a single color, not a spectral series flash. Sometimes flow structures or flat bubbles can be seen under a microscope.

Diamonds treated by these technologies have special provisions on clarity classification, as shown in the first section of Chapter 15.

Four, jade processing methods and identification.

As a kind of high-quality jade, the demand for jadeite is increasing, while the top-grade products with bright colors and high transparency are very rare in natural products. The contradiction between supply and demand has prompted the price of jadeite to rise rapidly. For many years, people have been trying to increase the color and transparency of jadeite by various artificial improvement methods to improve its commercial value and usability. Common methods are: discoloration, dyeing, yellowing and glue injection. In the jewelry industry, jadeite is divided into A, B and C goods.

1. heat-treated jadeite and its identification

The heat treatment of jadeite is called baking. Generally, the color of jadeite is deepened by heat treatment, and red is often added. Red jadeite is also a favorite variety, but there are not many red varieties in nature, and pure red ones are rare. Most of them are tan. The purpose of heating is to remove brown or brown and get a better red color.

The step of heat treatment is to put the cleaned and dried samples into the furnace. Generally, the temperature in the furnace does not need to be too high, and it can be heated in the air. In order to ensure the uniform heating of the sample, it should be placed in a transparent container or away from the heating element, and the heating rate should be slow. It is best to observe while heating. When the jadeite sample begins to slowly change color and pig liver color appears, it will slowly cool down, and the jadeite will appear red after cooling. For jadeites with different textures, the operation time and temperature should be specifically adjusted. In order to obtain a bright red color, after the jadeite is completely cooled, it can be soaked in bleaching powder solution for several hours and chlorinated, which can increase its splendor.

The red color of baked jadeite and natural jadeite is colored by hematite (ferric ion), which is formed by dehydration of limonite. The difference is that natural products lose water slowly under natural conditions, while baked products lose water quickly under heating conditions. It's hard to tell them apart. If you distinguish it, you can only distinguish it by people's feelings, that is, natural products are more transparent, while baked products will be slightly worse, giving people a feeling of "dry hair".

2. Production and identification of Class C goods

Color is the main factor that determines the value of jadeite. The purer the green, the higher the value. But most jadeites are rarely green or light-colored, so people use dyeing and coloring, and the most commonly added colors are green and purple.

The steps of coloring are: firstly, select jadeite with certain pores (jadeite with high density and dense structure is difficult to add color), clean and dry. Then put it into the solution of dye (such as amino dye) or pigment (such as chromate) and soak it for about 2 weeks at the temperature below 100℃. Time depends on the depth of color penetration, the size of emerald and the number of pores. Finally, some colored jade pieces are dried, and the surface is stained with wax to make the color distribution softer. Both dyed and colored green jadeites are sold as C goods. The coloring method of purple jade pieces is similar, except that the dye or pigment is changed to purple.

For jades with the same appearance, the value of goods A and C is very different, so it is very important to identify goods C. Generally, color filters, absorption spectrometers and magnifying observation are used. If it appears dark brownish red to brownish pink under the color filter; A thick black absorption line appears in the red part of the absorption spectrum near 650nm; Under a magnifying glass or microscope, we can see the green network structure in the microcrystal gap. One of the above three phenomena can be identified as C goods. However, jadeite without these phenomena can't be determined to be not C goods if it doesn't change color under the color filter, because people's dyeing technology is very clever now, and it may be that a new dyeing method has been adopted, which needs to be further determined by various means. At present, the most suitable method is infrared spectrum test, and C goods will have obvious pigment absorption peak.

3. Production and identification of B goods

Because jadeite is a polycrystalline aggregate, there must be a small amount of metal ions such as iron and manganese between tiny crystals, and the oxides of these ions are mostly dark oxides, which greatly affects the color and brightness of jadeite. In particular, dark brown, gray and other spots and defects appear at the bottom of jade, which makes jade look dirty and obviously reduces its value. In order to solve this problem, people used chemical rinsing to remove stains, which led to the emergence of B goods.

There are two main steps in the production of commodity B. One is to remove yellow, which is also called cleaning or "drenching yellow". The method is to wash and soak the selected samples with strong acid (such as hydrochloric acid and dilute sulfuric acid), and constantly replace the new acid solution, which usually takes 2 ~ 3 weeks. Observe the sample until the yellow color basically disappears. After the topaz is decolored, the color is bright, the green is prominent, and the background color is obviously white, but the transparency is not good, the water head is poor, and it is cracked. 2. Glue injection: neutralize and dry the yellow jadeite, and glue injection for reinforcement. Emerald is yellow after acid elution. Although the overall appearance has not changed, the fine structure has been seriously damaged and the strength has obviously decreased, which needs to be strengthened. Put the heated sample into the glue, keep the temperature below 200℃ in the drying oven, and make the glue evenly penetrate into the green gap. Commonly used adhesives are plastic and colorless epoxy resin. Finally, polishing to remove the surface glue visible to the naked eye.

The identification of B goods is very difficult, which requires a variety of observation, instrument testing and comprehensive analysis.

(1) Observe the color, luster and structure of the gemstone carefully. B goods are brightly colored, but unnatural. Sometimes when yellowing is not good, there is a yellow tone at the bottom; Different from the glass luster of natural A goods, B goods often have resin luster, which reduces the amount of reflection and weakens the luster; After cleaning and injecting glue, the structure of B goods changed greatly, and most of them were loose. Side light observation shows that rough white filiform structure appears in the white part, and obvious concave-convex structure appears on the gem surface.

(2) Determine the density and find out the difference. The density of jadeite is 3.30 ~ 3.36g/cm3. Theoretically, the density of glue injection for goods B after cleaning should be lower than the original one. However, due to the limited amount of glue injection and the fact that the density of jadeite as a mineral aggregate is not a constant value, the density change of B goods often cannot exceed the scope of jadeite. So the density change is only a reference value.

(3) Ultraviolet long wave test showed fluorescence. Some B goods have blue-white fluorescence under long-wave ultraviolet light, which is the reaction of injecting organic glue. If you don't inject fluorescent glue, there will be no such reaction, but at present, most B goods are fluorescent.

(4) Infrared spectrum test, comparing spectral differences. Nondestructive infrared spectroscopy can be used to detect B goods, which is the most effective method at present. Each mineral has a specific infrared spectrum. Because of the glue injection, the infrared absorption line of B goods is obviously different from that of natural jadeite. Different adhesives have different absorption lines, but not all of them are owned by the same product. Comparing the infrared spectrum of the test sample with that of the standard jadeite, the product with excessive absorption peak is B.

In practice, people often use some special methods to identify B goods, such as burning, which can turn B goods into black coke. , but all have shortcomings. In addition to the above three methods, there are various ways to improve jadeite, such as coating, veneer, fake skin and so on. There are many patterns and they are often renovated, but they are very unpopular.

Think about a problem

First of all, is it right or wrong?

1. According to the national standard, all dyed gems must be marked "to be treated" in the appraisal report.

2. The method of changing the color of sapphire spots or bands at high temperature is called "diffusion heat treatment".

3. infrared spectrometer can only distinguish a part of jadeite and B.

4. According to the national standard, any kind of jade carving dipped in wax can be sold without indicating (processing) after the name of the gem.

5. On the appraisal certificate of any dyed gem, according to the national standard, the name should be followed by (treatment).

6. The effect of dyed agate is stable, and it doesn't need to be marked and treated when it goes on the market.

7. Topaz with radiation discoloration shall be declared as "treated" when it goes on the market.

8. Recycling turquoise belongs to gem treatment.

9. Topaz can be listed after irradiation discoloration and heating fixation.

10. The change characteristics of solid inclusions in diffusion treated sapphire are similar to those of heat treated sapphire.

Second, multiple choice questions

1. High-quality imitation pearls are coated with multiple layers on the round core: ()

A. fish scale paint

B. silver powder

C. made of white porcelain pigment.

2. At present, the allowable radioactive residue of irradiated topaz (ex-factory market) is: ()

A.70 ~ 15 baker

B.70 ~ 15 roentgen

c.70~ 15γ

3. Distinguish jadeite from B jadeite filled with inorganic glass: ()

A. color filter

B. Microscope

C. infrared spectrometer

4. The coated diamond improved by vapor deposition method has the following characteristics: ()

A. Smooth without texture

B. There are parallel lines

C. There are cloud-like lines

5. In order to find out whether there is glass filler in ruby, it is advisable to choose: ()

A. bright lighting and oblique lighting

B. Lighting in dark areas

C. Reflective lighting

6. When judging whether a diamond is a laser drilled diamond or a filled diamond, you'd better choose: ()

A. bright lights

B. Lighting in dark areas and inclined lighting

C. Reflective lighting

7. When distinguishing between diffused sapphire and blue sapphire, it is important to observe: ()

A. whether the growth line or solid content has changed.

B. Contrast the color differences between edges, tips and surfaces.

C.is there stubble on the ridgeline?

8. Ruby and dyed ruby should be: ()

A. color filter

B. Microscope

C. spectroscope

9. In legal trade, which of the following optimized emeralds does not need to be declared: ()

A. colorless oil-filled

B. Injecting colored oil

C. plastic injection

10. The instruments that must be used to distinguish jadeite from grade C jadeite are: ()

A. Magnifier or microscope

B. Charles filter

C. specific gravity balance

1 1. At present, the radioactive residues carried by irradiated topaz in China are based on the Regulations on Radiation Protection of Industrial Products for Daily Use, and the radioactive tolerance standard is ().

A.70 baker

B.30 baker

c.50γ

12. Identify natural and radioactive blue diamonds and use ().

A. thermal conductivity meter

B. conductivity meter

C. refractometer

13. Jade B is under ultraviolet light: ()

A. there must be fluorescence

B. no fluorescence

C. no fluorescence.

14. Sapphire with unclear arc band after heat treatment is written as () in the column of identification certificate name.

A. artificial sapphire

B. Artificial sapphire (treatment)

C, synthesizing sapphire by heat treatment.

15. The best way to change colorless topaz into blue topaz by using the principle of color center coloration is ().

A. radiation heat treatment

B. Diffusion heat treatment

C. dye

D. coating

16. Using infrared spectrum to distinguish between jadeite filled with glue and jadeite not filled with glue is a test ()

A. is the structure damaged?

B. mineral composition of jadeite jade

C. cations in jadeite jade

D. organic anionic groups

17. When green zircon turns blue after heat treatment, the atmosphere to be controlled is: ()

A. Neutrality

B. oxidation

C. Reduce

18. Emission of radiation sources used in cathode ray luminometer: ()

A. electron beam

B. Optical inspection

C. gamma rays

Third, multiple choice questions

1. Emerald (treatment) means: ()

A, treating with strong acid and alkali, adding polymer glue and pigment

B.as long as it has been treated with strong acid and alkali.

C. Adding color after heating

D. washed

There are fillers or pigments in the cracks.

2. According to the "national standard", the word "disposal" must be added to the name of the following gemstone: ()

A. sapphire treated by thermal diffusion

B. heat-treat rubies

C, heat-treating to remove variegated colors to generate pink beryl.

D. dyed agate

E. The turquoise is dipped in wax to deepen the color.

Fourth, fill in the blanks

1. The improved gem should meet three standards (), () and ().

2. The two main steps of making Jade B goods are () and ().

3. Topaz is obtained by () treatment and subsequent () treatment.

4. There are (), (), () and () easily confused with jadeite in natural jadeite without artificial dyeing.

5. The jadeites that have been artificially treated are (), (), () and ().

6. The optimized jewelry and jade can be divided into () and (), in which () can be named as the original jewelry and jade, while () is marked with the word () after the original jewelry and jade.

7. There are four ways to optimize diamond processing: ① () ② () ③ () ④ ().

8. The optimized ruby processing method is: ① () ② () ③ () ④ ().

9. The two items () and () in the sapphire optimization treatment method must be marked with () when marking and selling.

10. In artificial products, the code name YAG is () and CZ is ().

1 1. Basanyu (Mountaineering Jade), a jadeite variety often encountered in the market, is characterized by (), () and ().

12. Commonly used manual processing methods to improve rubies are () and ().

13. A colorless standard round diamond-shaped gem with excellent fire color, diameter of 5.8mm and weight of 1. 15ct, which may be a () gem.

14. Under the irradiation of reflected light, the main distinguishing features of Emerald B are: (), () and ().

15. At present, there are (), (), () and () optimization methods for corundum gemstones.

16. When evaluating the effect of gem improvement (optimization or treatment), at least three aspects (), () and () should be considered.

17. The commonly used methods to improve the color of pearls are (), () and ().

18. The identification feature of sapphire after high-temperature diffusion treatment is that it may appear in the form of (), () and () in diiodomethane leaching solution.

19. The filler of jadeite (treated) can be () or () or ().

20. The natural jadeite treated with strong acid or alkali is called B jadeite, which is filled and consolidated with () or (). Its main feature is that () was destroyed and some other substances were added.

The main treatment methods of 2 1. sapphire are () treatment and () treatment.

22. The main purpose of making grade B jadeite by soaking in strong acid or alkali is to remove () and ().

23. If the colorless lattice contains a small amount of (), it can produce purple after irradiation.

24. Diamonds with the GE POL logo engraved on the waist edge are colorless diamonds with the () color removed.

25. Ruby heat treatment often uses () atmosphere to eliminate () hue and () inclusions.