Helga Hufflepuff’s Cup was a magical item created by Helga Hufflepuff, one of the founders of Hogwarts. It was a small golden cup with two finely-wrought handles with a badger engraved on the side and a few jewels. The badger is the symbol of Hufflepuff House.
The cup was passed down through the Hufflepuff family, and through the centuries made its way to Hepzibah Smith, a descendant who kept the cup as a priceless heirloom. In 1946, Smith showed the cup to Tom Riddle, a.k.a. “Lord” Voldemort, who was working at Borgin and Burkes at the time. He ultimately transformed the cup into his fourth Horcrux, using Smith’s murder as the tool.
This is obviously a replica as the original was broken with a basilisk by Hermione and Ron.