Doing a search I found that a couple people have had good results polishing their cultured marble countertops. I don't really know what our bathroom countertop is made from, it was purchased at Menards a few years ago, and it's plain white. Looking at current offerings at such stores, it looks like it's cultured marble or onyx. I'll be getting my stuff soon, including Optimum HC and P. Think it would be safe to give the polish a go on the countertop? It has a lot of scratches.