I am away from home so cannot investigate. I notice your refract IORs are very different than what I showed. Since the effect comes from those values, perhaps you should try my numbers before you attempt to come up with your own deviations.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)