We've had medium gray plaster for 2 years and are very happy with it. It does have mottling that we think adds to the natural look of our pool. It's made by adding black mable dust so it's not supposed to fade like the ones colored with dye. Colored quartz can also be added which is not supposed to fade and provides a wider range of colors. I suggest asking the contractor to see some real pools (new and a few years old) since everyone has different tastes. You can also step up to the pebble and other high end finishes.