According to Kimichik, gold-plated metal is when “a smaller layer of 14K gold [is] applied over a base metal.” The amount of 14K gold can vary, but the minimum “must be 0.5 microns of gold,” says Kimichik. Most of the time, base metal is brass, but some companies might opt for a sterling silver base to keep earrings and other jewelry pieces hypoallergenic.  “Gold-filled jewelry has about 100 times more gold than gold-plated jewelry,” says Kimichik. “It contains layers of 10K, 14K, [and] 18K gold wrapped around the base metal and should have a 1:20 ratio with the base metal,” she adds. She also notes that gold-filled has a much longer lifespan compared to gold-plated and that the base metal can be any type of metal, including brass or sterling silver.  In addition to gold-plated and gold-filled, there is also gold vermeil, which has more requirements compared to its filled and plated counterparts. “The gold plating used must be at least 10K, and the base metal must be sterling silver,” says Kimichik. “The plating thickness for gold used must be a minimum of 2.5 microns,” she adds. This is the more expensive option out of the three, but it will also last longer.