Reply To: Light Physics › Forums › Gemology › Light Physics › Reply To: Light Physics June 30, 2016 at 10:34 pm #2729 Alan BalmerKeymaster @alanbalmer Scott, I missed this when you first posted it. I’m no expert on the subject*, but I know someone who is. Get Tom Herbst’s books “Amateur Gemstone Faceting”, available at Amazon. What you’re looking for is in Volume 2, but get Volume 1, as well. *Though I did struggle through Born and Wolf’ “Principles of Optics” when I was a young lad.