Being new to laser engraving, I read carefully a lot of your post.
Having received with my kit (eleksmaker A3, laser 1600mw, 445nm) a pair of green glasses for free, I also wondered what it was about the quality of this one.
Having a spectrophotometer at work, I was able to make a small test to see what wavelength was filtered by this glasses.
You can see the result in the attached image.
At 445 nm 99.6% of the light is filtered.
It will seem that these glasses work very well for lasers of 445nm.