Galleon
From Harry Potter Wiki
Galleon is the most valued coin of the wizarding currency. One Galleon is equal to 17 Sickles or 493 Knuts. Galleons are made of gold.
Although the rate of Galleon aren't mentioned in the books about Harry Potter, it's considered that one Galleon is equal to five pounds.[1]
[edit] Fake Galleons
Galleons made of Leprechaun gold were common at Quidditch games where Leprechauns are the mascots for the Irish team. These galleons are occasionally in temporary circulation (they vanish a few hours after appearing), but goblin experts at Gringotts can differentiate them from real ones.
Rubeus Hagrid used Leprechaun gold fake Galleons at a Care of Magical Creatures class, while teaching students about Nifflers' ability to hunt for shiny objects like coins.
Hermione Granger fabricated fake Galleons for members of Dumbledore's Army as a means of conveying clandestine communication about the time of future meetings.
Ludo Bagman used Leprechaun gold to pay Fred and George after their bet resulting in them blackmailing Ludo with no luck.
