What does the gold necklace of the just bought? What does it mean?

Hello,
zj represents CICC. 1 represents the production area code.
The laws of Hong Kong:
Thousands of gold: "Thousands of gold" or "AU999.9" are engraved on the accessories with a gold content of 999.9.
The foot gold: The gold content is not less than 999th of the thousandths, and the "foot gold" or "AU999" is engraved on the decoration.
Domestic laws:
Thousands of gold: The gold content is not less than 999), and there is a "Thousand Foot Gold" or "AU999" seal.
Fed the gold: The gold content is not less than 990 % of the thousandths, and it is engraved with "foot gold" or "AU990".
1. Thousands of gold refers to the gold content of 99.9%of the gold content. In other words, thousands of gold is gold.
The gold: The gold content is not less than 990. The mark is "Foot Gold", "990 Gold", "GOLD990" or "G990".
2, 9999 gold is gold with gold content or more than 999.9 ‰, commonly known as the imprint of "Wanzu Gold Series" is "10,000 -foot gold" or "999.9 gold". Therefore, it must be a thousand -foot gold, but the gold is not necessarily the gold.
3, K gold's "K" is the writing of the term "karat" of the foreign language. The complete statement is this: Karat Gold (that is, K gold), "AU" or "G" is used internationally to express it. Symbol of goldenness (that is, gold content). K gold (or opening gold) is a alloy made of gold and other metals. The characteristic of K gold jewelry is that the amount of gold is small, the cost is low, and it can be made into various colors, and it improves hardness and is not easy to deform and wear. K gold is divided into 24K gold, 22K gold, 18K gold, 9K gold, etc. The most common "18K gold" in my country's market, its gold content is 18 × 4.1666 = 75%, and the imprint on the accessories should be "18K" or "AU750"/"G750".