THREE key details on your 10p coin could make it worth 3,000 times its value, as five sold for £340 at auction yesterday.
The pre-production 10ps were issued from the in 1992.
At the time, UK and Manx 10ps were reduced in size and sold at RWB in Royal Wootton Bassett.
The pre-production trial coins were intended to help businesses calibrate their vending machines and other cash systems before standard coins were .
The items seller requested them from the and retained them for more than 30 years.
It is thought that and they have rarely been offered for sale, making them to collectors.
The rare 1992 Isle of Man coins can be identified by three hard-to-spot
Below the portrait of , there are no initials – ordinary 1992 Manx 10ps have the letters ‘PM' underneath her neck.
There are rounded tails on the number ‘9's in the date, compared to the pointy tails on standard 10ps.
There are the letters ‘AA' on the top of the inverted foot of the triskeles design on the tails side.
The triskeles or triskelion is an ancient symbol associated with the Isle of Man, often represented as a spiral of three legs.
It's often shown on Manx coins, which are popular with coin collectors because of their unique designs.
Since they are the same size as UK coins, Brits sometimes find Isle of Man change in their change, meaning a rare one could easily be mistaken for a standard British 10p at first glance.
Christopher Collects, a modern coin expert for RWB Auctions, said: “These Manx coins are exceptionally rare, with just a couple of hundred ever made.
That makes them so much scarcer than coins you might know about, like the Kew Gardens or Salmon 50ps.”;
