Actress Lindsay Lohan and her best friend Sam Ronson have sparked further rumours that they are lovers after the latter bought her friend a commitment ring.

Sources say Ronson bought a Cartier diamond ring worth $22,000.

“Ronson took Lohan shopping to celebrate her 22nd birthday. It is not an engagement ring, simply a token of her commitment,” said an insider.

Lohan and Ronson have been friends for a long time but rumours that they might be romantically involved started swirling when they were spotted kissing and cuddling at the Cannes Film Festival in France.