If the sink is a high gloss cultured marble, it may dull the finish. My preferred method is to use a soap scum remover such as scrubbing bubbles or lysol power bath. Spray it on, let sit for several minutes, wipe clean and rinse
Hello Hawaiianei, you could use vinegar to remove the hard water stains, or CLR which is designed to do the same. Depending on what the finish is, you want to be careful what you are using.
Soaking with CLR doesn’t do much