>>1557300Permanent marker will be less noticeable than the scratch but still very different. You might not see it as quickly when you walk into a room but the colour is very obvious when handled under natural and artificial light. Only in dark room can't you easily tell the difference. A black marker will look purple by comparison as they use a mix of ink colours to make black markers.
Others have said use acrylic ink makers. That might be more obvious as the reflectivity of acrylic inks is could be different to that of the glossy black paint there. Same even if you get an enamel or other oil based paint. Testing is your only way to tell what's best. Watch out for brush or nib strokes if using those, as well as the pooling that can leave raised edges if brushing or spraying.