Lighting design engineers have been illuminating things with magic glowing powders for at least eighty years. Anyone who got beyond the surface layers of LED lighting in the last ten years will recognise the graph that follows. Whether we think of it as a wobbly line of woe or a testament to the vastly improved technology that now lighting up the world, it recognisable as the output of a white-emitting (or approximately white-emitting) LED.
These images are deliberately idealised examples, to avoid the impression that we are seeking to promote or criticise anyone in particular, but they represent roughly what white LEDs have looked like since their inception. It not completely clear what is going on here, because the details are likely to be considered trade secrets by the companies….