Speculation began when the Czech beauty was spotted wearing a huge diamond ring on her finger. Nemcova, 27, was scene with the ring while she was shooting an ad for Hewlett Packard in New York this week.
A spokesperson for the couple, who have been dating since last June, made no comment on an engagement.
Before falling into the arms of the You’re Beautiful singer, the supermodel was dating photographer Simon Atlee. The couple were on holiday in Asia in December 2004 when the tsunami occured. Nemcova lost her love in the tragedy and she herself was hospitalised.