Cree has already hit 300+ lumens per watt at room temperature and 1W power throughput, and are showing no signs of slowing. The problem with LEDs is not wave issues, but the Auger Effect where electrons recombine with the LED junction material instead of going through the electron hole.
However, CRI is still meh. For gem work, you want sunlight or incandescent, nothing else is acceptable because you need a true blackbody radiator. LEDs work fine for isolating and orienting stars, adularescence, schiller, and sheens, but are horrible for tenebrescent gems, some dichroic gems, and such.
Also, some LED-covered wavelengths are still utterly useless when compared to other sources. UVB LEDs at their best are only about 2% efficient. You might as well stick with a raw phosphor-less fluorescent tube with glass filters for UVC and UVA on it at that point, you'd still push roughly 30% efficiency.
Red LEDs are also still rather meh on the efficiency scale.