SPECULATION is rife that Rihanna and Chris Brown are engaged after she was spotted in London with a huge diamond ring on her wedding finger. There have been rumours before that the couple were to wed but Ri' and CB (who are just 20 and 19) have always denied they are even in a relationship According to The Sun, Chris proposed over the New Year as the couple performed at the O2 Arena. Rihanna was joined by Brown on stage at Elton John's New Years Eve party. In December Billboard Magazine named Chris Brown the biggest artist of 2008 for his album sales, downloads and radio play. - MTV