Ludo Bagman paid off bets to Fred and George Weasley, as well as many other winners, including goblins, at the Quidditch World Cup using Leprechaun gold. Rubeus Hagrid used Leprechaun gold coins in a Care of Magical Creatures class where he was introducing the students to Nifflers, and Gregory Goyle's attempt to pocket them secretly was thwarted when he heard they would disappear eventually.
Ron Weasley paid back Harry Potter in Leprechaun gold for the Omnioculars in the Quidditch World Cup, not knowing that Leprechaun gold would disappear until Hagrid told him later in Care of Magical Creatures class. Ron felt bad about this, but Harry told him it was no problem.
Behind the scenes
- The concept of leprechaun gold vanishing after a time may draw from the concept in Welsh folklore that money or other gifts given by fairies will vanish or turn to worthless objects if you tell anyone where you got them from.