A terrified woman woke up to find a person in her bedroom.
The 68-year-old was woken in the early hours of Sunday morning at her home in Eversley Road, Bexhill.
Police say the person stole distinctive gold antique rings – one with a pink diamond and the other with rubies. A string of freshwater pearls was also taken.
Detective Sergeant Paul Graham said: "This was obviously a terrifying experience for the woman and we are working closely with her to establish the full facts of the incident.
“We are keen to speak with anyone who may have been in the area around 1.35am or have information that could assist the investigation. The suspect is described as slim and dressed all in black except their hands, which were small, and they had a well spoken voice. The victim said they were young but is unsure if they were a man or a woman.
"Anyone with information should contact Sussex police on 101 or email email@example.com quoting Operation Fathom. Alternatively contact the independent charity Crimestoppers on 0800 555 111."