# Precious-Opal and/vs X-Ray Diffraction

by PMH
Tags: diffraction, opal, reflection, transmission, xray
 P: 4 (My (old) background is math & computer science. I've long loved (mostly) precious opals - for thier esthetics, lapidary potential, synthesis (which I've done), and how the play-of-color ("PoC") is produced.) I recently did another couple of passes on the latter in the process of trying to figure out how the contra-luz flavor of PoC is produced. (Contra-luz is transmission PoC rather than reflection PoC.) I was trying to do the research efficiently, which came down to decisions on how much I had to go back to learning ... optics? ... from scratch all the way up to what I need for this effort -vs- trying to understand as much of it as I needed to just by trying to make more & more sense out of material that's intended for people who have such a background. One of the places I happened into is X-Ray ~optics~. But it was hard to make the correlations betw/ this range of wavelengths and the visible (for opals). ...even though, put that way, it sounds like it should be trivial. Problem was that uses of X-Rays tend to be about their transmission - whereas for opal, I was trying to get from reflective to transmissive. I couldn't see, eg, how the Bragg equation (or its derivations) could (& should) be used for the transmission case. Maybe I should admit that I avoided reciprocal space. (& hope to be able to continue to do so for this research, although I could be convinced otherwise, I guess) Surely there are cases where X-Rays are reflected rather than transmitted by the diffraction, but I never did find out what those cases are. (so that in itself would serve pretty well as the official question for this thread)
 Sci Advisor P: 5,468 Google "photonic bandgap material" and "artificial opal". You should find infinite relevant links to choose from.
 P: 4 Thank you, Andy. Now I'm sorry that I didn't make it clear that that's exactly what I have been doing - for many months. In fact, I'm pretty confident that I've figured out the answer; what I want is to check it via seeing how actually knowledgeable people in the field of X-Ray optics treat it. (as opposed to me - not you)

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