The difference between Gold-Filled, Gold-Plated/ Vermeil & Solid Gold...

Process Description
Gold Plated Thin layer of Gold coated to a  base metal.
Gold Vermeil Thick layer of Gold applied/ coated to Sterling Silver.
Gold Filled Very thick layer of Gold permanently bonded applied by pressure permanently bonded to a base alloy/s.
Karat Gold Pure Gold mixed with metal alloys