Our local Cognex distributor usually helps with lighting. They offer to come look at the application and then test with parts back at their facility. This back and forth helps to make sure the camera works. Less headaches for me as the end user.
Lighting and wavelengths and proper setup of a vision system is a pretty big topic. Whoever your vendor is, should be able to assist with this if they are any good at what they do.
I'm sure you can do some reading on the topic as well if you google enough as well.
In a previous job where I was doing a lot of vision stuff, I mostly utilized CCS Lighting and they have a ton of options.