A conwoman allegedly stole £4.2 million of diamonds from a luxury London jewellery store by using “sleight of hand” to discreetly swap them for pebbles, a court has heard. 

Lulu Lakatos, 60, has been accused of posing as a gemologist as part of an elaborate heist of seven precious stones from the Boodles store on New Bond Street in central London in 2016. 

The gems included a 20-carat heart-shaped diamond valued at more than £2.2 million and a three-carat pear-shaped fancy pink diamond worth £1.1 million.

In the opening day of the trial against Lakatos on Tuesday, Southwark Crown Court heard that the 60-year-old Romanian was sent under the alias “Anna” to inspect the diamonds by a group posing as wealthy Russian investors. 

Lakatos was escorted to the jewellers’ basement meeting room on March 10 by Nicholas Wainwright, Boodles chairman, and Emma Barton, the firm’s own gemologist.

When inside the room, Lakatos purported to examine and weigh the diamonds before individually wrapping them in pre-cut tissue paper and placing them inside opaque boxes, the court heard.

The boxes were then placed in a zippable purse, which was padlocked shut, and Lakatos placed the locked bag inside her own handbag when Mr Wainwright went upstairs to take a call from the Russian buyer, known as “Alexander”.

The other Boodles employee in the room, Ms Barton, told Lakatos that she was not allowed to transfer the locked bag containing the diamonds into her bag and asked her to place it back on the table. 

“The woman posing as Anna looked confused and did as she was told,” Philip Stott, prosecuting, told the jury. “But, unseen by Emma Barton, however, it seems what happened was it was swapped for an identical locked bag and that duplicate bag was placed back on the table.”

Ms Barton informed Mr Wainwright, pictured below, what had happened and, as a precaution, Mr Wainwright asked the defendant if he could look into her handbag.

“She allowed him to, and Mr Wainwright reassured himself that the bag was relatively empty with nothing unusual in it,” Mr Stott told the jury. 

The duplicate bag was then placed inside the shop’s safe and the defendant walked out of the store at 12.05pm.

But the following day, after money for the diamonds had failed to arrive from the Russian investors, Boodles sent the padlocked bag to be X-rayed and inside each of the opaque boxes was a small pebble instead of a diamond, the court heard. 

By then it was too late. As soon as Lakatos had left the store, she allegedly moved a purse-like object from her handbag to the handbag of an unknown young woman who had been browsing in the nearby Ralph Lauren and Cartier stores.

Credit: Eddie Mulholland for The Telegraph

Mr Stott said Lakatos, who lived in the Saint-Brieuc region of north-western France, discarded her hat and scarf and changed her clothes in a pub toilet, switching her dark coat for a light one, assisted by another accomplice.

She then used her own passport to leave London on the Eurostar, the court heard, and all the thieves allegedly involved in the heist were out of the country within three hours of the offence taking place. 

“The diamonds had been stolen by the defendant by sleight of hand,” Mr Stott told the court.

“The conspiracy in which she is alleged to have played an integral and central part was one of the highest possible sophistication, planning, risk, and reward.”

Lakatos, who was born in Romania but lived in France, denies conspiracy to steal.

The trial, which is set to last three days, continues.