I tested a GE "Basic LED" ligtbulb (9.5w 60w-equiv, warm and cool). It's their cheap line of bulbs (not dimmable. No CRI mentioned.). I think GE makes it exclusively for Lowes. I don't see anyone else selling it.
I attached an example PDF showing how I'm planning to memorialize the test results (you have to look hard for it. This forum's theme doesn't make links and things stand out well). This is the only one I have, so I can't summarize anything about it. Eventually I'll put this on my Google Drive with other results. I'll have a summary PDF (rank the test results, and link to each test-result PDF). I need to do some more and see how it goes together. (I need to baseline a CFL too. It surprises me how people still hang unreflected CFLs in the air. Comparing a globeless LED lightbulb to one of those is attention-getting. It's like 4x the light for 33% less electricity. It's enormous. At least when I measured lumens.).
When I measured lumens, I was just looking for the brightest light per watt. It will be interesting if any lightbulbs stand out as better in terms of PAR. Getting back to CRI, if you watched one of those DIY spectrometer videos, the guy illustrated how "white" on a computer screen is really just red, green & blue. He points his tube-meter white screen and it's just 3 spikes. It's not a nice blend of the entire spectrum from blue to red.
I wonder if CRI has something to do with that. Maybe that kind of "white" has low CRI because it's such a lousy match to the full spectrum of the sun? And, the higher the CRI, the more complete. If true, then maybe that would be reflected in PAR? (I should try to measure the PPFD of my laptop screen. ha. And the lumens. If there's a big difference, that might mean something.).
Yes, I watched a little of it. Absolutely interesting stuff.
I understand the LCD coloring. My guess is that many different single wavelength diodes could work in symbiosis, creating a very high CRI or even a CRI of 100.
Three single wavelength diodes, can not (but still produce a white light).
The downside is that producing some colors results in a low umol/j. Green, for example, has a low value when created with monochromatic diodes. Red and blue are very efficient and white diodes are just blue diodes with a phosphor coating that will convert some of the blue light into other wavelengths, through fluorescence.
Comparing a white light from a computer screen with white light from a LED-bulb will most likely be very difficult.
If you want to compare umol/j for 3 white diodes vs one red, one green, and one blue diode of the same caliber, I could probably help you figure that out (if I can find the old tests).
Lumens favours green/yellow light and only tells us how bright a light is to us humans.
umol/m2/s or PPFD, measures all wavelengths/photons equally.
As different wavelengths are produced with different efficiency, the PPFD will change based on what colors the light consists of.
It can be:
10% blue, 50% green and 40% red
40% blue, 50% green and 10% red
Both could potentially show roughly the same lumen/LUX, while the light with 40% red can produce a greater PPFD since red light is more energy efficient than blue.
Just an example but you get my point.
So yes, the PPFD will most likely be reflected in the CRI.
Btw I did find some notes. I don't recall if it was Epistar or Bridgelux LEDs, but I've tested a couple of different wavelengths in a sphere to see how they compare.
385nm 0,04 PPF/W -> PPE -> umol/j
Mix and match any way you like.
By the way, it is not included losses for inefficient drivers, lens caps, etc. So the real numbers are lower than this.
Lens caps can produce a greater PPFD/W, but will produce a lower PPF/W.