What does A mean?

Thousands of gold: The amount of gold content is not less than 999, which is called thousands of gold, which is the highest value of jewelry named names. The mark is thousands of gold, 999 gold, GOLD999 or G999. Foot gold: The gold content is not less than 990. The mark is "Foot Gold", "990 Gold", "GOLD990" or "G990". To buy gold jewelry, we must first recognize the quality inspection logo of gold jewelry. Most of the gold jewelry sold in the market is equipped with inspection signs from quality inspection institutions, which clearly marked the gold content and weight of the jewelry. 999 gold is also called thousands of gold, and the gold content is not less than 999 ‰; 990 gold is called sufficient gold, and the gold content is not less than 990 ‰; the gold content of 22K gold is not less than 916 ‰; the gold content of 18K gold is not less than 750 ‰ ; The gold content of 14K gold is not less than 585 ‰; the gold content of 9K gold is not less than 375 ‰. In particular, consumers need to remind consumers that the colors of 18K gold jewelry are yellow, white, red and other colors. White 18K gold is alloy of gold and nickel, zinc, silver, copper and other elements. White K gold jewelry is not a platinum (platinum) product. The mark of gold jewelry includes manufacturers' code, materials and purity, such as: X Gold 990, XAU990, X -foot gold, etc. Among them, letters X are the manufacturer code. When making jewelry with different materials or different purifications, materials and purity should be represented separately. When the jewelry cannot be printed due to too thin or too small, it should be attached to the logo containing the imprint content
Is to be adopted as a satisfactory answer.