In June this year, I bought a PT950 platinum necklace in a Cuihua gold shop in Liaoning. I hardly ever wear it. Because I don't like it very much, it was sold in June+February, 5438, and it became black when it was on fire. I was dumbfounded. The owner of the recycling station really didn't change color, but it clearly said PT950. Alas, the description is impure. Finally, only 18K gold can be used.