Oh yeah, and on the subject of the image. The reason you probably prefer it without tir is that this kind of image does not really benefit from it. If you have a brighter environment with gems cut a certain way then by all means use it, but if not... don't. Also, your refraction may be up too high, is it on 133 or 155? The more refraction, the greater tir will effect it, in this case, very negatively.