groundFungus:
For reference.
Most modern high-brightness green, blue and white LEDs are all GaN with about the same forward voltage,
just different quantum well dimensions (and a blob of phosphor for white). 3.0 to 3.2V or so. Otherwise
forward voltage in volts is pretty much the same as photon energy in electron-volts...
Unbranded LEDs are typically rejects from production lines, and will have a lot of variation... You get
what you pay for usually.