Sandy wrote, "Actually I was being very precise. [...] The use of the definite article "the" in this sentences limits the scope of the comparision to the specific items identified."
Sandy, sorry about that - you're right. I did much better on the math portion of the SAT than I did on the verbal portion.
But I do want people to consider that we can't make assumptions about wavelengths which we can't see based on colors we can see. Tools for measurement are going to be needed to be certain. That may mean using a densitometer or using printing paper to determine density.