The confusion over the gold chain in Shakespeare's A Comedy of Errors is, like the majority of the conflict in the play, the result of a case of mistaken identity.
Antipholus of Ephesus orders the chain to be made as a gift for Adriana. However, the goldsmith Angelo mistakenly delivers the chain to Antipholus of Syracuse, believing him to be the customer, and says he will collect his payment later.
Of course, when he later approaches the correct Antipholus for payment, Antipholus of Ephesus claims (honestly) that he never received the necklace at all. But Angelo does not know that there's a pair of identical twins both by the name of Antipholus running around the city and believes Antipholus of Ephesus is trying to cheat him out of paying. Antipholus of Ephesus is then arrested.
Angelo then runs into Antipholus of Syracuse out and about (when he believes him to be his brother and that he should be locked up) and wearing the very necklace Antipholus of Ephesus claimed to have no knowledge of.
The confusion is not resolved until the twins are reunited, and it becomes clear that each had been repeatedly mistaken for the other.