Well, first we MUST know the type of GID, especially the color.
The way photons work is an incoming photon has no charging effect if it's below the minimum energy (above the maximum wavelength). Also any energy in excess of its threshold is wasted.
For most colors, it needs UVA and the 405nm LEDs are by far the most efficient and cost-effective chargers. The more expensive deeper blacklight LEDs are only nice in that they're mostly invisible instead of a brilliant purple cast of a 405. But they're typically not going to produce as many active photons as the 405, and cost 10x more. As per rule #2 above, the extra energy of the shorter wavelength mega-expensive "deep UV" LEDs has no added charging effect.
Red glow powder (red being the lowest energy color) can be charged by green wavelengths. That's the exception. In fact- this is cool- if you charge up green glow powder, put it next to discharged red, it will charge the red! Also a green laser pointer charges red which is pretty awesome.
Blue LEDs can charge green, but it's not very effective. I believe this is due to the bell-curve nature of the distribution, where only a minority of the photons are above the threshold energy.
Or maybe the individual glow particles have a bell curve on the exact threshold needed to excite them and only a minority of the glow particles will respond to blue. Actually that makes more sense because most blue LEDs have a fairly tight emitted color. As such- and now that I think about it, this has to be it because glow powder does NOT have a tight emitted color wavelength- a brighter blue LED WILL NOT result in greater charging. Because its wavelength will still only be able to excite only a portion of the glow particles, and a dimmer blue LED might have already fully charged the blue-reactive particles anyways.