I have a kitchen sink made of artificial stone. I love it because I can get rid of most stains after soaking it overnight in water in which a sterilising tablet has been dissolved.
These are tablets used to sterilise baby bottles. And if the tablets are safe enough for baby bottles, they are safe to be used for the sink.
Using lemon juice to clean the sink is also safe and effective.
You can make a paste with ½ cup of powdered borax and the juice of half a lemon. Dab a sponge in the mixture, then rub and rinse with running water. This will work on porcelain or stainless sinks or those made of other materials.
For artificial stone sinks, you can also use baking soda to clean stains. You can do this by making a paste of baking soda and water and using a scrubbing sponge to rub the sink, before rinsing it thoroughly.
I tackle stains when they occur, but I also wash my sink every night after doing the dishes.
For ordinary cleaning, dishwashing soap and warm water will do the job most of the time.
I add a spoonful of stain remover to a soap solution and soak my dishcloths nightly in the sink. That cleans not only the cloths, but also the sink.
However, if you have washed raw chicken or other meat in your sink during the day, don't wait.
Wash it immediately, including the taps. Do this carefully with hot, soapy water to get rid of the bacteria found in raw meat.