An insurance firm has offered a £50,000 reward for information about an aggravated burglary at the home of a Staffordshire billionaire.
Thieves broke into the Broughton Hall home of Phones4U founder John Caudwell on 1 November and hit him with a rod.
The men stole cash and jewellery, including a Chanel diamond watch, gold Breitling watch and diamond necklace.
They ran away through nearby fields. Two people have been arrested and bailed in connection with the burglary.
Det Ch Insp Tim Martin said: "We have a dedicated team of detectives pursuing a number of lines of inquiry.
"We would like to hear from anyone who has been offered any jewellery in suspicious circumstances, or knows of its whereabouts."
The thieves broke in while Mr Caudwell, his partner Claire Johnson and a female worker were in the house. They hit him with a metal bar causing cuts to his head and elbow.
Two men from Liverpool, aged 43 and 33, were arrested shortly after the break-in and were bailed pending further inquiries.
The insurance firm wanted to be anonymous but had offered money for information resulting in a conviction, police said.