Is white gold really gold?

White gold is the name of a class of jeweler’s white alloys used as substitutes for platinum. Different grades vary widely in composition, but usual alloys consist of between 20 percent and 50 percent nickel, with the balance gold. A superior class of white gold is made of 90 percent gold and 10 percent palladium. Other elements used include copper and zinc. The main use of these alloys is to give the gold a white color.

Gold leaf is pure gold that is hammered or rolled into sheets or leaves so extremely thin that it can take 300,000 units to make a stack one inch high. The thickness of a single gold leaf is typically 0.0000035 inch (3.5 millionths of an inch), although this may vary widely according to which manufacturer makes it. Also called gold foil, it is used for architectural coverings and for hot-embossed printing on leather.