Of the same apparent intensity to a rod? If they're not, you'll guess correctly based on apparent brightness, and your brain fills in the colour based on memory of which colours of paper are around.

There are low levels of cones out to the periphery, but of such level as to be unreliable sources. For example, this notes that some monochromatic light is misidentified peripherally but not foevally, and that frequency discrimination drops by a factor of 50 or so.