Hi Zandra, I'm not sure you'll be able to find a paint that holds up in a sink. But this video does show you how to make your crushed granite sink look like new again - https://www.youtube.com/watch?v=wmxa10PEDMc Maybe that would be a better option?
Paint won't hold up in a sink.
Take a good photo to the paint dept. of your home improvement store and ask them. They carry the latest and best products to do a professional job.
Paint will not work in a sink because of the cleaners and the water. It will chip off almost immediately.