Breguet talks about their "silvered gold" dials (including the one on my Marine). Rolex says that the Hulk Sub's dial is made of "green gold." Can anyone explain to me (in simple, monosyllabic terms) what these mean and how they're done? I realize that both are essentially made of gold (although it's not clear what percentage is gold as opposed to other alloys) that is somehow processed/treated to change the color, but that's about where it ends for me. Is it a chemical process? Mixture of alloys? Food dye??