"No, our white gold cases are not rhodium-plated. Actually, we use a gold/palladium alloy, whose colour is white enough. Maybe that it is a little less bright than a plated finish, and it is more expensive than other alloys because of the palladium, but we have 2 advantages:
No allergies due to the presence of nickel in the metal (by the way, the steel we use is also nickel-free)
No need to plate again after polishing (to remove scratches for instance)