Gold has good physical properties, stable chemical properties, high malleability and scarcity. It is not only a special currency used for reserves and investment, but also in the jewelry industry, electronics industry, modern communications, aerospace industry and other sectors. Important material. The following is the content of professional knowledge about gold jewelry organized by the editor, I hope you like it!
(1)Gold jewelry classification
1. “Pure gold” jewelry
”Pure gold” is usually divided into pure gold and thousand pure gold. Red-yellow in color, soft in texture and dazzling luster But absolutely pure gold does not exist, as the saying goes, “gold is not pure.” With modern science and technology, reagent gold with a purity of 99.9999% can be extracted specifically for use as standard chemical reagents. Due to the high production cost of reagent gold, only from the use value of jewelry, the use of reagent gold to make jewelry is of little significance. At present, there are three types of pure gold in the Chinese market: “Four Nine Golds”, with a fineness of 99.99%; “Three Nine Golds”, with a fineness of 99.9%, commonly known as Thousand Pure Gold; and “Two Nine Golds”, with a fineness of 99%, commonly known as Pure Gold.
2.K gold jewelry
K gold is an alloy made by adding some other metals to pure gold to increase the hardness, change the color tone and lower the melting point. Due to the different proportions of other metals added, the color, hue, hardness, ductility and melting point of K gold are all different. The characteristics of K gold jewelry are that it uses less gold, has a low cost, and can be formulated into various colors, and is not easy to deform and wear. Especially after the gems are inlaid, they are firm and beautiful, and show the precious beauty of the gems. Therefore, it is widely popular in many cities in our country. The color of K gold jewelry is relatively rich. At present, red K gold, orange K gold, yellow K gold, green K gold, blue K gold, cyan K gold, purple K gold, gray K gold, black K gold, White K gold, white K gold is similar to platinum because of its color and luster, especially with a layer of rhodium, which is more elegant and can be fake, but the price is much lower than platinum, so it is favored by many people. There are three main series of formulas for white K gold, namely: gold and palladium, gold and nickel, gold and silver, or their combination alloys, which can form white gold.
(2) Imitation gold jewelry
1. Gold-plated jewelry
Gold-plated jewelry is mostly made of silver or copper, and the surface coating is gold. The luster of gold replaces the original color of the original material, thereby increasing the ornamental value of the jewelry.
The gold content of gold plating shall not be less than 14K, and its thickness shall not be less than 0.5 microns. Gold-plated jewelry is generally lighter in body and harder when bent. In addition, a thin layer of jewelry is rubbed hard on sandpaper to reveal the base color. After fire, the color that turns white is silver, and the color that turns black is copper.
2. Gilt jewelry
Gilt is a kind of jewelry making method that appeared in ancient times. It is to dissolve gold in mercury, and then evenly spread on the surface of the jewelry, dry it and bake it with charcoal fire to make the mercury volatilize, and then use agate to calender the surface. Become a gilt product.
3. Gold-clad jewelry
Gold-clad jewelry is made of silver, copper, lead, zinc and other alloys to make a blank tire, and then mechanically or other methods are used to firmly wrap the gold foil on the surface of the metal product substrate to obtain a gold covering layer, which is called gold-clad. The gold content of the gold-clad shall not be less than 14K, and its thickness shall not be less than 0.5 microns.
(3) Maintenance of gold jewelry
1. When wearing gold and silver jewelry, avoid contact with hard objects and pull hard. Due to the low hardness of gold and silver, it is easy to be scratched or broken when it comes into contact with hard objects, which will damage the decorativeness of jewelry.
2. Wear jewelry in chemically contaminated areas. At the same time, try to minimize contact with perfume, hair oil, toilet water and other cosmetics. Once contacted, the surface of the jewelry will easily corrode and cause spots or discoloration. In order to maintain the luster of gold jewelry, you can often add a small amount of detergent in warm water and place the jewelry Brush gently with a soft brush, rinse with clean water, then wipe with a soft cloth and dry.
(4) Inspection of gold jewelry
The jewelry mark should contain the manufacturer’s code, the name and content of the precious metal material.
2. Appearance quality
is mainly the inspection of the overall shape and processing quality of jewelry.
3. Jewelry weight
The price of gold jewelry is calculated based on weight and processing fee. The weight of jewelry is one of the important indicators. According to the standard, the unit of measurement of jewelry weight is gram, and the allowable error of a single piece of gold jewelry is 0.01g.
4. Gold content
The gold content in jewelry is an important indicator of its quality. There are many methods for testing gold content, which can be divided into chemical analysis methods and instrumental analysis methods. According to whether the jewelry is damaged during the inspection process, it can be divided into non-destructive testing method and destructive testing method. The daily inspection in the jewelry quality supervision department is generally based on the non-destructive testing method, and the density method is combined with X fluorescence spectroscopy and electronic probes. And other large-scale instrument analysis. Market supervision and spot checks are mainly destructive testing, and the fire assay is currently the national testing method for determining the gold content in jewelry in my country.
(5) The physical properties of gold
Luster Red yellow, fineness above 95%; normal yellow, fineness about 80%; blue-yellow, about 70%; yellow slightly gray, about 50%.
Hardness Mohs hardness is 2.5, which is similar to human nails.