[Robocop]

Purely hypothetical query. If metals and other dense materials show, under X-ray a blue colour and less dense organic compounds show green. If you were to dissolve gold in aqua regia. Will it show as green or blue?

[Enthalpy]

Welcome, Robocop!

I don't grasp what shows a colour. Is it the material itself, say by fluorescence, which would need a badly strong X-ray intensity? Or does a screen show these colours after computer processing of a detector data?

Some X-ray imagers only represent with a colour palette the absorption of one X-ray source. Others use several X-ray energies to distinguish the elements, for instance to detect objects rich in -NO₂ or -NO₃.