Chow Tai Fook: The first Zhou jewellery and gold shop was founded in Hongde Road, Guangzhou in 1989, 1929. Its name is Chow Tai Fook Gold Store, which mainly deals in gold jewelry, which means great wealth and great wealth.
Rust:
Although gold itself has not been corroded, it has a strong chemical affinity with sulfide, and it is easy to adsorb hydrogen sulfide acid gas in the air, and its surface may be dark, such as orange and brownish red. The production of gold products needs to go through many complicated processes.
Take gold bars and coins for example. They all go through the processes of smelting, tabletting, blank cutting, blank pressing, quenching, acid frying, polishing, pressing and edge pressing. The working environment cannot be a vacuum environment. Every link may encounter dust and impurities in the air attached to the blank of the product. These impurities may become erythema after being stored for a period of time without quenching and pickling.
Don't touch gold products directly with your hands during daily appreciation. Once erythema appears, you can ask professionals to burn gold products on the fire, which can solve the problem and basically do not affect the quality of gold products.
In addition to red spots and black spots, gold products sometimes have white spots, especially gold jewelry.
This is mainly because consumers often put gold jewelry in drawers at will. When it comes to mercury, it will immediately form a large area of white spots, especially when women use cosmetics containing mercury. Long-term contact will also produce white gold products. If you wear it with platinum and silver jewelry at the same time, it will also produce white spots after long-term friction.
Four textures:
Mature gold is the gold after smelting and purifying raw gold, which is generally high in purity and fine in density, and some of it can be directly used in industrial production.
Common are gold bars, nuggets, ingots, various ornaments, utensils, gold coins, industrial gold wires, sheets and plates.
Because of different uses, the required fineness is different, or because there is no purification equipment, only unpurified gold is melted, or the purity is not enough to form gold with different fineness. It is customary to divide mature gold into pure gold, red gold and colored gold according to its fineness.
Gold with a fairly high purity after purification is called pure gold, and gold generally refers to pure gold with a purity of over 99.6%.
1. Red gold and pure gold have similar meanings, but the standard of red gold varies with time and place. Gold with a purity of 99.6% sold in the international market is called red gold. Domestic red gold is generally between 99.2% and 99.6%.
2. Non-ferrous gold, also known as "secondary gold" and "tidal gold", refers to gold with low fineness. Due to the different contents of other metals, the purity of these gold is as high as 99% and as low as 30%.
According to the classification of other metals, ripe gold can be divided into solid gold, mixed gold and K gold. Clear gold means that gold is only mixed with silver, regardless of its fineness. Clear gold is more common in gold bars, ingots, nuggets and various utensils and gold ornaments.
3. Mixed color gold means that besides silver, gold also contains other metals such as copper, zinc, lead and iron. According to the different types and quantities of metals, it can be divided into small mixed gold, large mixed gold, bronze mixed gold and lead mixed gold.
4. K gold means that silver and copper are mixed in a certain proportion, and the pure gold calculated according to the formula is 24k. Generally speaking, the more silver in K gold, the bluer the color; If the proportion of copper is large, the color is purple.
The percentage represented by the value of k is only an approximation, and it is not required to be very accurate. Traditionally, even k values are used, such as 24K, 22K, 20K, 18K, etc. 18K means that 24 parts of alloy contain 18 parts of gold, which is equivalent to about 75%. Calculation method of K gold: The calculation formula of converted gold content of K gold is: K value ÷24× 100% (that is, K value × 4. 1667%).