Most common lenses used in vintage Ray Ban sunglasses are G lenses, G15 to be precise.
The G lenses come in a wide variety:
Constant Density G15, Constant Denisty G31 (mid grey), Full Mirrored, Top Gradient Mirrored, Double Gradient Mirrored, Diamond Hard G15, Chromax G20, and several special mirror colors mostly for Wayfarer and Cats 1000 series. Colors like green, purple, gold, silver, blue. I will probably miss some.