Well, you MIGHT have. But, while I've seen the idea thrown around before, I've never actually seen it done before:

What a lovely Bane's Heart style magenta.

The classic red. Picture distorts it a little, but that's pure red LED on the main blade, just like a BR saber.

Man, I wish purples photographed better. This one is VERY DVA looking.

Pure GB blue.

A really, really bright yellowish-green.

And, in person, this is as dead on a match for my EG Apprentice V4's blade as you could ask for.
This, saber friends, is a beautiful work of lightsaber art. A Flamberge V2 with Emerald driver, V4 sound, and AS side blades...coupled with LEE filters, I have a world of choices for my crossguard saber.
Not every filter works, though. Some are simply too dark, some are way too light, and some...well, you just have a hard time matching hue and brightness to a usable standard. Orange and Yellow, for example, are giving me a hard time, but I haven't done more than one of each color of filter yet, it takes time to cut the blasted things out, then play around in the launcher to try to match it.
Haven't yet found the filter to match straight up CG yet, but I will, or close enough.
I'll be testing and refining some more in the coming days, and adding more pics, as well as my settings for each filter that I find a usable setting to match.
Love this thing. I can be Jedi, I can be Sith, I can be every shade or nuance between, too.