Russell Brand to propose to Katy Perry?

Russell Brand has sparked rumours that he is going to propose to girlfriend Katy Perry.

The comedian, who has been dating 25-year-old Perry since September, was recently seen shopping for a diamond ring.

"His face lit up when he saw this one particular diamond ring. He put it on his ring finger and gazed at it for ages," one onlooker at Cartier told the Herald Sun.

Brand has previously said of Perry: "I'm a one-woman gentleman now. She's amazing. I'm having a right laugh, she's a good person to spend time with and it's changed me, it's made me stop doing stuff that I probably shouldn't have been doing."

Perry used to date Gym Class Heroes frontman Travis McCoy, while Brand has previously been linked to stars such as Playmate Holly Madison, model Kate Moss, singer Britney Spears and actress Teresa Palmer.