First of all, Au750 is 18K gold. . The symbol of platinum is (PT950 or PT900), and Au750 turns red because the platinum coating on the surface falls off. Because 18K gold is an alloy composed of 75% gold and 25% other metals. The real color is yellow. Only a layer of white metal will be white. So you can go to Liu Fuli and have them repackage. It will change back to its original color.