Rihanna's rumored boyfriend Chris Brown has bought her a $100,000 diamond necklace.

The 'Umbrella' singer, who has been constantly romantically linked to the R'n'B star and was recently seen kissing him in a KFC fast food restaurant, was thrilled to discover Chris had splashed out on a ruby and diamond necklace from jewellers Jason of Beverly Hills.

Jewellery designer Jason Arasheben revealed: "Chris went for the heart theme. He said, 'She's going to love this because she loves hearts.' "

Rihanna, 20, was so impressed with her sparkling gift that she has ordered a diamond-encrusted cross for 19-year-old Chris from the same jewellers.

Jason added to America's OK! magazine: "Rihanna gave specific instructions about Chris' gift. She was very particular about wanting the cross to match his other jewellery."

Rihanna was first linked to Chris in February after he attended her 20th birthday.

Later that month, the pair enjoyed a romantic holiday in Jamaica and could barely keep their hands off each other while cooling off in a pool.

They are also believed to have got matching star tattoos on their necks during their break.

Rihanna has previously denied she is dating Chris, insisting he is like a brother to her.

She said: "We are best friends, honestly, like brother and sister. I won't say that we're just friends - me and Chris are really best, best friends."

Chris also claimed he has no interest in pursuing a relationship with Rihanna, saying: "People keep asking me, 'What's the deal?' I'm like, 'There's no deal. No deal.' We're just friends."