They have released an image of the man they believe to be Vinko Osmakcic, a Croatian national thought to be responsible for a number of high-value diamond thefts throughout Europe.
At the 2017 Masterpiece fair at the Royal Hospital Chelsea, three rings were stolen with a combined value of over £2m from the stand of Switzerland-based jewellery dealer Boghossian.
Det Sgt Chris Taylor from Kensington and Chelsea CID, who is leading the investigation, said: “This was a well-planned and audacious theft committed in the middle of a busy art fair.
"We are re-releasing the image of Mr Osmakcic in an attempt to trace him. It is highly likely that Mr Osmakcic may be out of the UK, possibly in Europe. He may also be known by the following names: Vinko Tomic or Juro Markelic.”
The items taken were a cushion-shaped diamond ring, a vivid yellow cushion-shaped diamond ring encased in smaller oval and round-shaped diamonds, an emerald-cut diamond ring with purple and pink stones, and four pear-shaped diamonds. All three rings have diamond-encrusted bands.
Anyone with information should contact Kensington and Chelsea CID on 020 8246 0122 quoting Operation Hestia or report information via Twitter @MetCC. Information can also be given anonymously by calling Crimestoppers on 0800 555 111 or via crimestoppers-uk.org.