Are Petra and James Engaged?

The rumor mill was pushed into high gear on Tuesday when supermodel Petra Nemcova was seen wearing a beautiful diamond ring while shooting a Hewlett-Packard commercial in New York.

She was wearing the lovely sparkler on her left hand, which in a reasonable world would mean that she was engaged to her boyfriend, musician James Blunt. But this is Celebrity World, so we really have no idea what's going on, do we?

Photo from People.