Morning and evening sun are best, with the sun behind you. Clouds are nice, as they keep the shadows at bay, but, you loose the sheen.

I don't do anything in shade if I can help it. Sometimes the light is just too harsh and I will do shade, but, it is my last choice. I don't like the look of flashed photos. In shade, you really *need* some flash to get sparkle. I am not good at that delicate balance between sparkle and flash though.

Not many people agree with my methods, but, that is ok.