God save the Queen!
This coin is especially handy if you are in a Tube station and need to use the loo. ;-)
(A note about the chain: It is genuine 925 silver filled, which means that it will tarnish just like solid silver. Store it in a plastic zip lock bag if you want to keep it shiny, or just let it darken naturally. You can always polish it up with any brand of silver cleaner or a buffing cloth.)