Pressleys, in South Street, Worthing, was burgled on Sunday, June 8, at 9pm.
A large quantity of Pandora jewellery was stolen during the incident.
Police are now appealing for witnesses who may have seen anything suspicious in the area to come forward.
PC Alexandra Watt said there was a possibility someone had seen the break-in as it was still daylight at the time.
She said: “This high value burglary took place on a Sunday evening when it was still daylight so there is a possibility that the burglars may have been seen.
“Please get in contact if you saw anyone acting suspiciously in the area, especially near South Street and Marine Place alleyway which leads off Warwick Street.”
Any witness or anyone with information is asked to call 101 or email [email protected] quoting serial 1479 of 8/6.
Alternatively, call the independent charity Crimestoppers anonymously on 0800 555 111.