It's a fake substance made from plastics and calcium carbonate and pigments
To remove scratches from a polymarble sink, you can try using a mild abrasive cleaner or a polishing compound specifically designed for surfaces such as polymarble. Apply the cleaner or compound to the scratch and gently buff it in using a soft cloth in a circular motion. Rinse thoroughly and dry the sink to see if the scratch has improved. If the scratch is deep, you may need to seek professional help to repair or replace the sink.
To clean polymarble basins, you can use a mild soap or bathroom cleaner with a soft cloth or sponge to wipe down the surface. Avoid harsh chemicals or abrasive cleaners as they can damage the finish. For tough stains, you can create a paste of baking soda and water, apply it to the stain, and scrub gently. Rinse with water thoroughly after cleaning.