Prince George's £50,000 coin: Piece containing 1kg of gold among first set minted to commemorate a royal christening

At the foot of the coin is the royal motto "Dieu et mon droit" - God and my right. The £5 coin is available in silver - because the crossing of a baby's palm with silver is said to confer good health and prosperity to newborns - and gold - to commemorate the royal celebration.

William and Kate's son will be christened at the Chapel Royal, St James's Palace on October 23.

Dr Kevin Clancy, director of the Royal Mint Museum, said: "I think the designer, John Bergdahl, has done an excellent job of giving us something that is timeless. It's symbolic and it's got dignity about it.