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As for DMM's, I don't have fancy modern ones that can test white LEDs.
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You don't need a new and fancy DMM to test the LED's; as example, my DMM870(1998) gives 3.2v, and the 8060A gives 8V in diode testing mode, both enough to light up any LED's.
That's why I've asked to check your multi-meters, so next time you will know which is suitable for LED testing(is part of "Know your tools" training)
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif.pagespeed.ce._hfWAz_QHO.gif)
That's "new & fancy" to me!
My Fluke 77 won't turn on blue LEDs, either, as they also require 3.2v.
My "bodge tester", consisting of a 9v battery, a 360
![Ohms \$\Omega\$](https://www.eevblog.com/forum/Smileys/default/omega.gif)
resistor, a switch, and a small "junk" pin connector does, though!
(I dunno how I happened to have 360
![Ohms \$\Omega\$](https://www.eevblog.com/forum/Smileys/default/omega.gif)
resistors & not 330
![Ohms \$\Omega\$](https://www.eevblog.com/forum/Smileys/default/omega.gif)
, but that's what my junk box had!)
An old ADSL box teardown yielded some nice blue LEDs with long leads, plus two bicolour ones.(red & blue, so if I ever need a purple light, I'm in good shape!)
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/xgrin.gif.pagespeed.ic.QVVz6XIT20.png)