If you need to reflect blue light in order to prevent "something" from this waveband, as you formulate in a former question, you can use a filter. A filter is described by a transmittance spectrum. You can have a look at the following web site to define the filter(s) you need. http://www.leefilters.com/lighting/colour-list.html.
The choice will depend on the light source concerned (spectrum and heat production).