The couple -- who were rumored to have got engaged during a romantic trip to Mexico in October -- are taking their own designs to a top jeweler in the French city after they jet off in a private plane tomorrow.

The pair -- who are currently in London following Samantha's DJ set at exclusive London nightspot Chinawhite last night - are expected to return to the UK to make an official announcement.

A friend said: "It's something they've been working on and naturally they're really excited."

The ring designs are said to be "hip and edgy" rather than "flash and expensive".

Lindsay, 22, is supporting her girlfriend, the sister of producer Mark Ronson, as she develops her European music career.

Samantha was previously thought to have already presented Lindsay with a Cartier ring worth around US$100,000.