Police are appealing for information to find a diamond ring that remains outstanding following a man's conviction.
Jimmy Tippett, 46, (09.09.71) of no fixed address, was sentenced to two-and-a-half years' imprisonment at Blackfriars Crown Court on Tuesday, 9 January.
He had pleaded guilty to the theft on Friday, 5 January at the same court.
The theft took place during the afternoon on 14 March 2017 in the Hatton Garden area.
The ring belonged to Tatiana Sieff. Her mother, Jo Stoller - who was selling the ring on her behalf - contacted Tippett, who was known to her, and asked for his help to sell it.
He took possession of the ring before leading the Ms Stoller around Hatton Garden and central London. He then, unexpectedly, ran off with it.
The theft was reported to police, who launched an investigation leading to Tippett being located in Brighton. He was arrested on 10 June 2017.
Tippett has failed to reveal the location of the ring which could not be found during a search of his home.
Detective Constable Mark Pinder, from Central North CID, said: "Although the ring has been added to the Gemmological Institute of Americas (GIA) stolen database, a worldwide database for stolen diamonds, we are appealing for help from anyone who may have seen it, or bought it in good faith, so that we can return it to its rightful owner. This has caused Ms Sieff and Ms Stoller a great deal of upset, especially as the Ms Sieff is a ring designer and this was her first piece of work.
"Tippett knew exactly what he was setting out to do when he was approached by Ms Stoller and callously took advantage of the situation.
"We urge anyone with any information on its whereabouts to contact the police on 101, or call Crimestoppers anonymously on 0800 555 111.
The ring is described as an Emerald cut, J VS1 diamond ring set in platinum. It has a retail value of around £25,000.