If you've ever dropped something in your sink and it chipped. Don't worry about replacing the sink, instead you can buy a kit and do your own porcelain sink repair. The repair will be very good, but not flawless.
You can buy a repair kit at a home center. The kit has a filler material to bring the divot up to the level of the surrounding surface, and it has a topcoat glaze to give the repair a shine. Some kits have an all-in-one filler that you buff to a shine when done.
Start by sanding the damaged area with 220-grit sandpaper. Just don't sand beyond the damaged area or you can scratch the surrounding porcelain. Clean the area and let it dry.
The filling compound and glaze come in several colors packaged in bottles that look like nail polish.
Use a putty knife to fill the divot. Use thin layers of the compound and let each layer dry before adding the next.
Once you build up the divot, break out the 220-grit sandpaper again. Sand the area with a light swirling motion being very careful around the edges to avoid scratching the surrounding surface.
You can also use a single-edged razor and slice any high spots off your final layer before it dries too hard. You still will want to sand it after you slice it.
Once the leveling is done, glaze the top of the repair.
The bottle of glaze will have a small brush attached to the cap. The idea is to dab the glaze onto the patch to make it match.
The trickiest part is at the edges. The glaze is about the consistency of nail polish and will have the tendency to stay where you put it. Use as little as is necessary to blend in the patch.
Let it dry and then hit it with the sandpaper.
You can also apply the glaze in small thin coats until you get the desired effect.
If just the top layer of the porcelain has been chipped from the sink, you may be able to go straight to the topcoat glaze.
Like I said, the kitchen sink repair won't be flawless, but you can fool most people with it.