Isn't the led inside the button? I'd think that it would make little difference what color the outside nut would be, it just might help it glow on the underside of the panel more...
One of the plusses of lighting
leaf buttons is that the 'core' of the button itself is relatively skinny, this means the bezel is more easily lit from below (either Knievel-style or just from lighting from the bottom in general.)
With the microswtich buttons, you either light them up from the inside (which can cause some centralization of the LED beam) or you can try a Knievel-style side-lighting system, but even doing the microswitch buttons Knievel-style isn't quite as effective as with the leafs because of the design.
My guess is that JoyMonkey is trying an alternate-method to the in-the-button lighting, or he may just have just found that even with the in-the-button method, the black ring is blocking the edges of the beam's spread.