In the sale of finished jewelry in China, the state stipulates that jewelry should be marked with three signs, one is the composition of metal material, the other is the name of the seller, and the third is the size of the gem (this is only available when there are gems)

PT950, PT refers to platinum, and 950 is an alloy material with a purity of 95% platinum.

YH should be the name of sales. Where did you buy it? Most of them are abbreviations of pinyin. (YH28 is a series, and PT950 refers to purity) 28 may be the internal number of a certain style, which is convenient for inquiry.

You bought a platinum necklace, and the most important thing is that there is something wrong with the word PT950.

Personal opinion, for reference only.