The popular science written materials in this article are all sourced from professional textbooks such as “National Standard GB/T 16652 – 2017 Jewelry and Precious Stones – Nomenclature”, “Systematic Gemmology”, and “Gemmology Tutorial”.
Why are natural gemstones optimized and treated? Is a gemstone still valuable for collection after optimization and treatment? Let’s see how “Systematic Gemmology” answers these questions: Natural gemstones are non-renewable precious mineral resources. The reserves of high-quality gemstones are originally scarce (it is also possible that mining areas are monopolized by certain groups or institutions). After long-term and large-scale mining, the deposits of many high-quality gemstones are approaching exhaustion. In recent years, the global demand for natural high-quality gemstones has been increasing, leading to an increasingly sharp contradiction between supply and demand of high-quality gemstones in the jewelry market, and prices have been rising. Therefore, the research on artificial optimization and treatment technologies of gemstones helps to comprehensively utilize non-renewable precious gemstone resources. It can not only alleviate the supply-demand contradiction of natural gemstones but also fully explore their potential beauty, economic benefits, and social benefits. Nevertheless, after all, the value of such artificially optimized and treated gemstones cannot be equated with that of their corresponding natural gemstones (in some cases, the treatment of gemstones even involves fraud). With the successive emergence of new varieties of optimized and treated gemstones, relevant identification technologies and labeling issues have emerged. What is optimization and treatment? All methods, except cutting and polishing, used to improve the appearance (such as color, clarity, transparency, luster, or special optical effects), durability, or usability of jewelry and precious stones are divided into two categories: optimization and treatment. What is optimization? Traditional and widely accepted optimization and treatment methods that can bring out the potential beauty of gemstones. What is treatment? Non-traditional and unacceptable optimization and treatment methods. As can be seen from the above, although we often mention optimization and treatment together, they are actually two words with two different meanings. To put it vividly: Optimization is like putting on makeup, and treatment is like having plastic surgery. The purpose of optimization and treatment is to make originally ugly gemstones look better and more marketable! Here comes the key point: Optimized gemstones can be sold in the market as natural gemstones without any declaration; gemstones that have been treated must be declared as artificially treated and not natural gemstones when sold in the market. Representation methods of optimization and treatment The representation methods of optimization and treatment in “National Standard GB/T 16652 – 2017” Methods and categories of optimization and treatment Heat treatment (optimization) During heat treatment, the content and valence state of coloring particles are changed under high-temperature conditions, the internal structure of the crystal is adjusted, and some internal defects such as inclusions are eliminated to change the color and transparency of the gemstone.Heat treatment is a type of gemstone optimization method. It can be regarded as a repetition and continuation of natural geological processes, which can lead to long-term and stable improvements in the appearance characteristics of gemstones such as color, transparency, and clarity. Commonly heat-treated gemstones include: aquamarine, morganite, tourmaline, crystal, zircon, tanzanite, amber, etc.
Detection difficulty coefficient: High, not easy to detect. Filling: Fill the gaps, (open) fractures, and cavities of gemstones with colorless oils, waxes, glass, resins or other materials, or infuse gemstones with many pores and fractures to improve or change the clarity, appearance, and durability of gemstones. Filling is what we often call gluing (spot gluing, dipping gluing, casting gluing), and it may be the most common method of gemstone optimization and treatment today. Filling gemstones with colorless oils and waxes; filling the gaps of gemstones with a small amount of resin to slightly improve their appearance. This belongs to the optimization method. Filling a small number of fractures and cavities of gemstones with glass and artificial resins to improve their durability and appearance. This belongs to the optimization method, but a note should be added. Infusing gemstones with many pores and fractures with solidifying materials such as glass and artificial resins to change their appearance and durability. This belongs to the treatment method. Commonly filled and treated gemstones include: aquamarine, tourmaline, turquoise, labradorite, jadeite, sugilite, amber, agate, amazonite, lapis lazuli, malachite, larimar, beryl, charoite, opal, crystal, nephrite, garnet, chalcedony, fluorite, rhodochrosite, quartzite jade, etc. (The order is not ranked. The gemstones in bold are the major ones for filling.) Detection difficulty coefficient: Low, very easy to detect. In the “National Standard GB/T 16652 – 2017 Jewelry and Precious Stones – Names”, it is clearly stipulated that light filling is optimization and no explanation is required. Moderate filling is also optimization, but a note should be made. High filling is treatment and should be clearly stated. The regulations of the national standard regarding whether filling belongs to optimization or treatment. Therefore, when buying some gemstones that are often treated with gluing, don’t just listen to the one-sided words of some unscrupulous merchants. It is still necessary to go to an authoritative institution to obtain an appraisal certificate. Don’t believe the certificates provided by the merchants themselves, as these certificates often contain a lot of false information. For example, aquamarine. Some merchants always say that aquamarine has a lot of inclusions and fractures and is relatively brittle, and only by gluing can it be processed, and the whole industry is selling such aquamarine. Yes, low-end aquamarine materials do have a lot of inclusions and fractures and need gluing treatment to increase the finished product rate. Here, the merchants seemingly show their attitude, but deliberately avoid the filling degree. The national standard allows filling treatment, but it does not allow you to sell highly filled and treated gemstones as natural gemstones.The conclusion of the certificate shown in the image above can also be expressed as: Aquamarine Bead Bracelet (Filling), which is also a method of treatment representation. Do not assume optimization just because the word ‘treatment’ is not seen. Bleaching (optimization) involves soaking gemstones in chemical solutions to lighten their color or remove impurities. Bleaching, commonly known as acid washing, is a form of optimization and does not require disclosure.
Is it surprising? Many believe that acid washing is a terrifying treatment method, and some pseudo-scientific articles scare you with the claim of strong acid residue, which is purely nonsense. Gem processing involves a long process of heat treatment, grinding, and water rinsing, and even the strongest acid would have evaporated by then. Organic gemstones such as pearls and ivory, as well as other gemstones like jadeite, often undergo bleaching treatment. However, bleaching + filling = treatment, and this combination is considered a treatment method. The common B-grade jadeite is jadeite that has been treated with bleaching and filling. Irradiation (treatment) involves exposing gemstones to high-energy rays to change their color, and irradiation treatment is often accompanied by heat treatment. Irradiation treatment of gemstones can sometimes be stable, such as the vivid and stable blue color of irradiated topaz, which is not easily detected. Sometimes colors can fade and become unstable after exposure to intense sunlight or low-temperature heating, such as irradiated deep blue sapphires. Irradiation treatment is often used to treat diamonds with poor color, and various colors can be produced through irradiation treatment followed by subsequent heat treatment. Colorless topaz can be turned brown through irradiation and then turned into a stable blue color through heating. Any quantitative method cannot distinguish between colored and naturally colored topaz. Irradiation treatment can be used to change the color of crystals, with colorless crystals forming a smoky color through irradiation, and colorless iron-containing crystals producing a purple color, which can be turned into yellow crystals through subsequent heat treatment. Irradiation treatment is an optimization method for crystals, and this is an example of irradiation treatment. During routine gemological testing, these gemstones, which cannot reveal their color origins, do not need to be specified according to national regulations. This paragraph is selected from the ‘Gemstone Tutorial’. For the yellow crystal shown in the image above, even if it is irradiated and colored, it can only be considered a natural yellow crystal because its color origin cannot be revealed. The certificate can only be a natural crystal, as stipulated by national standards. This is not artificial crystal cultivation, which is synthetic crystal and is different from natural crystal. Dyeing (treatment) involves infiltrating gemstones with coloring substances (such as colored oils, dyes, etc.) to improve or change the color of gemstones. Dyeing treatment can allow coloring substances to penetrate the gemstones to achieve the purpose of producing color, enhancing color, or improving color.This treatment method is mainly used for the color improvement of gemstones with light colors and low values. Such gemstones usually have loose structures, are porous or contain a considerable number of cracks and fissures, allowing pigments to penetrate. For single-crystal gemstones such as crystals, to carry out dyeing treatment, there must be large fissures on the crystal surface or exposed inclusions.
If there are no fissures on the crystal surface, artificial “quenching and cracking” can also be carried out before dyeing treatment. Crackled crystal is made by this process. There are many types of gemstones treated by dyeing. For example: emeralds immersed in colored oil, quartzite dyed to imitate South Red Agate, lapis lazuli and other jade stones, crackled crystal, dyed kyanite, dyed magnesite to imitate turquoise, dyed phantom crystal, dyed strawberry crystal, dyed lapis lazuli, dyed jadeite, etc. The dyeing treatment of agate and chalcedony is an optimization method, and this is also an exception. Therefore, some unscrupulous merchants also sell dyed red agate as South Red Agate, and the sugar-core agate you like is also obtained after artificial dyeing treatment. Assembly (treatment): A gemstone finished product made by artificially assembling two or more gemstone materials together is called an assembled gemstone. Assembled stones are often made from thin slices of gemstone rough. Sometimes both parts of the assembled stone are natural materials, but more often only the crown of the gemstone is a real natural gemstone, while the pavilion is made of synthetic materials or glass, belonging to imitation gemstones. Coating (treatment): A thin film is applied or plated on the surface of gemstones and jade to change their luster, color, produce special effects, cover surface defects (pits, cracks, scratches, etc.) or protect the gemstones and jade. The coating treatment method is generally used on gemstones such as topaz, colored diamonds, and crystals. Coating natural crystals to imitate tourmaline looks extremely realistic. The reason for using natural crystals for coating instead of glass is that there are some flocculent or acicular inclusions inside natural crystals, making it more realistic after coating. Coating a colorless film on the surface of natural organic gemstones to change the luster or for protection belongs to an optimization method, but it should be noted. Diffusion (treatment): Under certain temperature conditions, foreign elements are introduced into gemstones and jade to change their color or produce special optical effects. Diffusion treatment is another special heat treatment method, mainly for the treatment of colorless or light-colored corundum. By diffusing the required chemical elements into the crystal interior, color and starlight can be induced on the outer layer of sapphires or rubies. Diffusion treatment can be divided into surface diffusion and volume diffusion treatment. High-temperature and high-pressure (treatment): Treating gemstones and jade under high-temperature and high-pressure conditions is mainly used to improve or change their color.High pressure high temperature treatment is a novel optimization method that has gained attention in recent years. It can be used to decolorize brown diamonds that have structural defects caused by plastic deformation.
Common gemstone, jewelry, and jade enhancement methods and categories: