Bill Byford asked if I could provide more information about this coin weight. On one side is a very stylised image of a late medieval ship; the other side is blank. Bill said it weighs in at 6.49 grams and he thought it could belong to the reign of Edward IV.
A useful little book on coin weights is English Weights, an Illustrated Survey by Norman Briggs. Some early examples are illustrated on page 27, including one for a noble, which matches Bill’s find. This bears an image of a late medieval ship with a fleur de lis at the left-hand side of the mast.
Briggs suggests that this weight could have been introduced when the new coinage of ryals and angels began in 1465. Just before this, nobles and quarter noble were struck from 1461 to 1464. However, few can have been made as examples of the noble were excessively rare until a further 62 were found in the Fishpool Hoard on 22 March 1966. You can read all about this truly fantastic hoard on this website in my article Largest hoard of hammered gold coins ever found.
Therefore, Bill was correct in thinking his find could date from the reign of Edward IV. The noble of Edward IV weighed 6.99 grams, so at 6.49 grams this coin weight is well below what it should be. In my experience it is not unusual for coin weights not to be up to the correct standard but this one is well off the mark.
I haven’t traced a similar example being offered for sale but I would stress that very few coin weight sell for high prices, even when they are very rare. This one is in decent condition with clear imagery but I wouldn’t price it any higher than £50.