All the Chemlights seem to be too weak.
They light up in Nightvision pretty strong, but only the Yellow chemlight emits a somewhat visible light.
You need to throw 4-6 of them at the same place to start seeing them without NVG.
Although they are just used for marking and not ambient lighting, they are definetly visible from a long distance; but atm, you have to poke your nose on them too see them