ardilla:
I'm looking for 20 bright RGB LEDs for a project. Each will go inside a 3" Japanese paper lantern. I tried the LEDs that come in the Arduino Starter Kit and they aren't nearly bright enough for this.
I find 10mm RGB LEDs are much brighter than 5mm ones, even though they look similar on paper.
For a lantern you probably want a wide viewing angle (140 degrees) and clear plastic, not diffused.
The figures quoted by manufacturers are confusing, yes. There's a few ways they can inflate the numbers by quoting narrower viewing angles or whatever.