[RedDevil]

Originally Posted by johnlvs2run

The two most important criteria for full spectrum lighting are the CRI (color rendering index), and the color temperature rating, measured in Kelvin degrees. The CRI rating goes from 1 to 100, the closer to 100, the more true the colors. A Kelvin rating of 5000 or higher produces more lumens (light registered by the rods of the human eye) and controls pupil size. Noon sunlight is generally around 5600 Kelvin, and 5000 Kelvin or higher light gives the appearance of substantially more light.

Halogen bulbs ~ 3200 K and 100 CRI

LED lights ~ 6000 K (posted by RedDevil) and 70 to 90+ CRI
As the lights posted by RedDevil are 6000 K, I would imagine their CRI is close to 100 as well.
I've been using LED lights in my home for years, used full spectrum before that, and the LED lights are better.

The K index stands for the apparent color of the light, rather than lumen.
It is directly related to the color a black object would appear to have when heated to that specific temperature; the hotter the more the color will shift from red through the spectrum to purple..
Halogens at maybe 2800 K appear yellowish.
My 5000K HIDs appear bright white.
The 6000K LEDs appear pale white with a hint of blue.
Some 7500K LEDs I have lying around appear purplish white.
12000K HIDs are full purple. And illegal as headlights.

Now HIDS have a natural color temp of around 6400K, but the color can be altered by adding certain salts or gases. As it happens, lowering the color temp enhances the lumen per watt in HIDs; as it takes slightly less energy to release a photon in the lower (reddish) region of the spectrum than in the higher region.

White LEDs are actually blue LEDs covered with fluorescent material that converts some of the photons to a lower spectral value.
(that's why they are yellowish or orange when off and white when turned on. The yellow/orange is the fluorescent material. Scrape it off then you have blue LEDs.)
A lower color temp requires a thicker layer of fluorescent material. Inevitably some light gets lost. So LEDS lose lumen per watt if the color needs to be warmer.

As for halogen the color temperature is caused by heat; the heating of the coil.
Most of the energy is lost to heat (infrared radiation) so the higher up the spectrum, the more effective they become.
Sadly, they also will fail quicker. And the efficiency in lumen per watt will not even come close to either HIDs or LEDs.

Edit: see http://en.wikipedia.org/wiki/Color_temperature
And the K stands for Kelvin; http://en.wikipedia.org/wiki/Kelvin