Thieves managed to get away with £1.8m worth of gold and diamonds after they smashed a hole in the wall of a jewellery shop in east London.
With the use of a sledgehammer and crowbar, the gang managed to get through to Joyalukkas jewellery shop in Forest Gate, Newham to carry out the raid.
The police have released CCTV images of the raid which took place between 3am and 6.40am on Monday 10 July.
Police believe three men entered the shop while others kept a lookout.
Detective Chief Inspector Andy Pallett, of Newham CID, said: “This was a meticulously planned and audacious raid on a jewellery shop with £1.8 million of items stolen.
“While we think it only took the suspects around 20 minutes to make the hole, it must have been noisy work and we would appeal for anyone who heard or saw anything suspicious to contact us.”
The men are described as being in their mid-30s, with one wearing a distinctive pink hoodie, one wearing a black coat and another wearing a t-shirt and shorts.
No arrests have yet been made, the Met said.
The force is appealing for information from anyone who may have seen the men or has been offered jewellery for sale following the raid.
Anyone with information should contact Newham CID on 020 8217 5414 or Crimestoppers anonymously on 0800 555 111.