In working with that line of opals from DH, I found that if I can see much cloudiness in the bead by the time it will go into the kiln, it will further opacify a great deal while annealing. So I try to keep the striking as limited as possible while making the bead, so that what the kiln adds doesn't overdo it. I do agree, though, that lighting makes a huge difference. That morning light is hard to beat for glass photography.