Like many other mints, the Royal Mint issues bullion coins in precious metals, having much higher intrinsic value than their face value. Most of these by tradition are measured in troy ounces of fractions thereof, but the mint also introduced metric coins measuring one kilogram of pure metal (they are actually fractionally heavier as a whole, to account for the small amount of other metal in the alloy).
The 1 kg silver coins are denominated as Five Hundred Pounds (£500), although their intrinsic (bullion) value is much higher than their face value. The coins vary in design depending on the occasion (they are "one-year" types usually issued in parallel with smaller denominations with the same reverse designs).
The coins are legal tender but are not intended for circulation. They are targeted at bullion investors or collectors who appreciate the special editions as pieces of art.
This commemorative 1 kg silver coin celebrates the christening of Prince George, the first son of the Duke and Duchess of Cambridge.
Prince George of Cambridge (George Alexander Louis) was born on 22 July 2013. He is the eldest child of Prince William, Duke of Cambridge, and Catherine, Duchess of Cambridge, and third in the line of succession to the British throne behind his grandfather (Prince Charles) and his father. As he is one day expected to become king, his birth was widely celebrated across the Commonwealth realms.
Prince George was baptised by the Archbishop of Canterbury in the Chapel Royal at St James's Palace on 23 October 2013. The font used at the ceremony was made for Queen Victoria's first child and the water was taken from the River Jordan. | 
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