Corian, manufactured by DuPont, is a hard material used widely in bathrooms and kitchens. Corian is nonporous and very durable, which make it ideal for kitchen and bathroom counters and sinks. Corian is said to be stain-resistant, but that is not always the case. The nature of a spill as well as how long the spill sits are contributing factors in Corian sinks becoming stained. But if your Corian material does get a stain, removing it is easier than you might think.
Pour a small amount of an ammonia-based cleaner on a cloth and wipe out the sink. Pay particular attention to the stained/discolored areas.
Rinse the sink. If stubborn stains are still visible, sprinkle on a mild abrasive cleanser and let it sit for several minutes. Scrub the stains with a scouring pad until they are gone.
Rinse the sink out well and dry with a clean, soft cloth to prevent water spots.