Depending on the method of dying it will result in different shades or casts: yellow, black, brown, red or green cast. You usually don´t see what cast it is on prewashed denim as the effect gets more apparent when the denim have been worn and washed. The picture above is from our concept store in Sydney and shows how the dry, unworn redcast fabric, that is almost a bit purple in the tint turns out to this clear and bright blue color and how the greencast fabric, dyed with green sulfur gives a deeper green/blue-ish fade. The more the fabric has been dipped in the indigo, the more apparent deep in the fade, after wearing and washing.
Have a great day!