When I was doing actual stained glass work, the thing that was emphasized was to make your color selections using the actual light conditions where it will be installed. In other words, if you were making something that will be placed in a window with the sun shining thru, then make your glass selection by holding the colors up to the window (or use a light table). I would do the same with the fabrics. Cut small pieces and tape them to the window to judge what they will look like. The tricky part with something that will be back lit sometimes and sometimes be front lit (like at night) is making it look good in both situations.