blue leds courtesy of Shuji Nakamura

Interesting video by Veritasium on blue LEDs:

source: https://www.youtube.com/watch?v=AF8d72mA41M

I remember reading a book called:  We Were Burning by Bob Johnstone, one of the stories covered the blue LED.  I've got that book around here somewhere, I'll have to find it and re-read it.

although I just might read it here:

https://archive.org/details/wewereburningjap0000john

Archive.org is quite handy at times !

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm