Is there a chemical formula for white gold?
Yes. "White Gold" is a mixture of pure gold with other metals. This changes the color as well as the value of the final alloyed metal. Some people like the color variations, some just like the cheaper price compared to pure gold. MOST gold used in jewelry is alloyed to some extent, because pure gold is really too soft for everyday use.
The actual compositions will vary greatly, depending on the desired look, workability and price of the final alloy. There is no single "formula" for white gold. The following link has a very good graphic demonstrating the changes in color and composition in gold compounds:
Colored gold - Wikipedia
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