Gold can be divided into four types according to grades, mainly including red gold, colored gold, mixed color gold and K gold, among which K gold is the most common and the most cost-effective. Compared with other varieties, it is more popular and suitable for daily wear.

Red gold is equivalent to pure gold. According to international standards, the gold content of red gold is generally around 99.2% ~ 99.6%, with high fineness, but the texture is very soft, which is not suitable for processing. Lottery gold, also known as "tide gold", refers to gold with low fineness.

Red gold is the best variety of gold with the highest gold content. Identification of pure gold:

First look at the color: the higher the purity, the darker the color. The fineness of deep red yellow is above 95%, light red yellow is 90-95%, light yellow is 80-85%, blue yellow is 65-70%, blue white is only 50-60%, and yellow white is less than 50%. The so-called seven greens, eight yellows and nine reds can be used for reference. So if the color is not deep red and yellow, it is definitely not pure gold.

Second, look at hardness: pure gold is soft and low in hardness. You can draw shallow marks with your nails, and you can leave teeth marks after biting. Gold ornaments with high color are softer than those with low color, and the more copper they contain, the harder they are. Bending method can also be used to test hardness. Pure gold is soft and easy to bend, and the lower the purity, the more difficult it is to bend.

Third, listen to the sound: real gold with a purity of more than 99% will beep when thrown on the hard ground, without rhythm and elasticity. Fake or low-quality gold sounds crisp and dull, generally making a "Dangdang" sound, with a lingering sound, and violently beating after landing.

Fourth, burn with fire: burn the jewelry to be identified with fire (do not melt and deform the jewelry), and observe the color change after cooling. If the surface is still golden, it is pure gold; If the color darkens or turns black to varying degrees, it is not pure gold. Generally, the lower the fineness, the thicker the color, and all of them turn black, indicating that they are fake gold ornaments.

5. Look at the logo: domestic gold ornaments are purified and prepared according to international standards, and stamped, for example, "24K" means "all red" or "thousands of gold"; 18K gold, marked "18k"; If the fineness is less than 10K, the K-gold seal number cannot be printed as required.

The above contents refer to Baidu Encyclopedia-Red Gold.