Don’t.

Black stainless steel is simply regular stainless steel with a thin coating of paint. At some point, you inevitably will damage that coating. While stainless steel can be buffed out to remove scratches, this is impossible with coated steel. And even worse, rather than having a minor blemish in the grain, now you have a highly-visible difference in color.

M it is actually worse, it is a film NOT paint and if scratch CAN PEEL !! Also each manufacture has different shades.