The couple visited a luxury jewellery shop in New York City, a day after the heiress turned 30, reported People magazine online.
"They shopped for engagement rings. They were really cute together. Paris was making comments about the rings and joking that her ring has to be at least 24 carats," said a source.
Hilton, who began dating the nightclub owner last summer, left the store with a very special birthday present.
"She walked out sporting a USD 25,000 white gold and black diamond encrusted ring," the source added.
The socialite has previously been engaged to model Jason Shaw and Greek shipping heir Paris Latsis.
Published 22 February 2011, 09:10 IST