Edinburgh auctioneers Lyon & Turnbull described it as an 18th century Jacobite secret service ring used as a 'signature' when travelling with correspondence from Charles Edward Stuart following the defeat at Culloden.
As no document from Bonnie Prince Charlie could carry a signature or seal (anyone found by government troops with such papers would almost certainly have been sentenced to death), a ring such as this accompanied the messenger to show that correspondence had originated from Charles.
The cipher of CR III 1766 denotes the year that Charles's father James died in France. Charles then considered himself the rightful King of Scotland and adopted the title King Charles III, rather than Prince of Wales, which even in exile he still used.
Bought by the vendor from a private museum in the Montrose area where it is believed to have been sourced, the ring was estimated to bring up to £3000 on February 13.
At £12,200 (plus 20 per cent buyer's premium), it was bought by an anonymous private collector, and will stay in Scotland.
