You need a dichro. Head to mliptack's optics GB and you can pick up dichros for bargain prices.
They work by working as transparent glass for one wavelength and being a mirror for another. You shine the wavelength they reflect, at them at 90% to the output beam and the one that passes from behind it in line with output.
Yes ! They are very near the exact color of argon ! Very pretty teal color. I had success at 12mw of 532nm and 15mw of 405nm. I have made a very nice RGB pointer using this setup. This is a beam shot coming through my prism. White light in......the true colors coming out in Pink Floyd style.