I believe you got it wrong
Nope, dilbert is correct about the cooling rates, although the statement about silver vs. any other color in the link he posted may be a bit misleading. While it's true that painted metal will cool faster than the unpainted metal, metal painted black will cool faster than metal painted white. But, dilbert also makes an incorrect assumption, which renders his conclusion invalid:
The interesting thing about white vs black is that if a white and black lens are both at the same temperature after being in the sun for some period of time then the black lens will return to a room temperature quicker than the light coloured one if they are both then taken into an air conditioned building.
A black lens and a white lens in the sun for the same long period of time will NOT
be the same temperature - the white lens will be cooler. In the sun, the temperature of each lens will rise until the heat gain from absorption reaches equilibrium with heat loss due to emission and conduction/convection. That equilibrium will occur at a lower temperature for the white lens (as much as 30-40% lower), due to lower heat gain because of the reflectivity of the white paint. So, when both lenses are taken into that air conditioned building, although the black lens will cool at a slightly faster rate
, the white lens has less heat to lose, and thus will reach room temperature sooner.