Why does a diamond look powder blue under black light?

Some diamonds will flouresce under a blacklight, but not all. It's just a matter of the chemical composition of the individual stoneWhy does a diamond look powder blue under black light?
When under black light, electrons in the carbon atoms of the diamond absorb energy and jump up to a higher electron shell(s), gaining potential energy. The electron is not able to keep the energy, and will release energy and fall back to it's original shell level. The energy released will have the frequency of blue light, so the diamond will look powder blue under black light. At least that's the physics explanation.