All precious metal jewelry sold in the US is supposed to be marked with its gold or silver content. Much, however, is imported, and some is hand-cast, thus looking for a marking is not a fool-proof indicator. There are also lots of fake markings, although I've found most to be legit.

Can real gold have no markings?

Does Real Gold Have to Be Stamped? In the U.S., there is a law that mandates that gold jewelry sold by a vendor must be stamped with a marking that indicates the item's karat number. The law also states that the real purity of the piece can deviate by up to 0.5 karats from the karat stamp.

How can I tell if old gold is real?

If it sinks, it's likely real gold. If it floats, it definitely isn't real gold. Real gold will sink to the bottom because it's denser than water. Gold will also not rust, so if you see any signs of rust you know your piece isn't real gold, and there's no worry about damaging your item if it is indeed real gold.