Or brown. Russian Jews are white, Ethopian Jews are black. Genetics change with the country you live in. Even if your ancestors made their home on the top of Mt. Hermon and were super white, if they had done their exile in Ethiopia, they'd be black now. Still not like purple black, which is why most Ethopian Jews are light-skinned black.
Good point Israel.
Lets say theoretically that a white man (such as a Jew in the exile) has children with a black wife and those children then breed for generations with other local blacks, that lineage of the white man's descendents would be entirely black skinned though will carry some of their white ancestor's genes.
Now let's say that the white man's black wife dies and he marries a chinese wife and has more children with her, those kids in turn breeding only with other Chinese, the original white man would then have both a black lineage, as well as a chinese lineage.
As travel was much more limited in the days of the early galut, it would be natural that such lineages of ancient Jews exist with very different skin colors, yet they will share the same genetic and cultural roots.
I have met Ethiopian Jews whose ancestors had no contact with whites for centuries, they are black as night, yet have blue eyes and Caucasian facial features. Skin color is not a determinating factor of what makes a person a Jew.
russianbred should have his mouth washed out with soap.