Quote ="Dally"I'd guess it would be theft to knowingly retain their consideration or property (ring) under the contract Cod'ead reports you entered into.
Sections 1 to 6 of The Theft Act 1968 may be pertinent.'"
It's all academic now, but there would be no chance of a criminal offence.
the property was not dishonestly appropriated. It was given and taken in complete good faith, and was in the possession of the donee (wife) without any involvement of the donor (OP).
The OP was not involved whatsoever with taking the item away from the jeweller.
To be guilty of theft you have to dishonestly appropriate something.
The OP didn't appropriate anything, ever, let alone dishonestly. He didn't even know it had happened.
His missus did appropriate it, but entirely and transparently honestly. She was not the "purchaser". She just innocently picked something up.
It would therefore be a purely civil matter. Clearly there would have been a balance debt due from the OP to the jeweller which they could have pursued him for, through the civil courts.