So I got into a mini-debate in science class today because I proposed that black holes aren't really black, they only look black because light can't reflect off them. But if you were to take the material that makes up that black hole and decrease it's density so that gravity isn't so strong that light can't reflect, then what color will this new object be? Think of it like this: if you put a red apple in a room that is completely pitch black, the apple will appear black but it's actually red (we just can't observe this because there's no light).
The material part of a black hole is (classically) compressed into a zero volume area, and almost all of the information of the matter that eventually became the black hole was dissipated away, so the original notion of your question is unanswerable.
There IS another sense in which we can think of your question, though. Black holes are known to shine light through a process known as Hawking radiation, which has a blackbody spectrum. To first approximation, stars are known to also have a blackbody spectrum.
The key point there is that the blackbody spectrum's color is determined by the temperature of the distribution. In the case of stars, this means that the hotter the star, the bluer the color of the star. For black holes, the more massive the star, the redder the blackbody distribution. For black holes that have masses anywhere near that of the sun, the "color" of the star will be very, very far into the radio edge of the light spectrum, and therefore, the black hole will not be visible to the naked eye.