This beautiful and grand palace could be a lovely and vibrant scene with a few simple touches of color. The stone of the palace could be a pale gray, with deeper shades of gray around the edges and towers. Additionally, the door and staircase could be painted gold for a classic, luxurious look. The sign "The Little Mermaid – Underwater Palace" could be painted a bright, royal blue. The fish in the moat can be a range of colors from vibrant blues, greens, pinks and yellows. Finally, the mermaid statues could be given a cool, magical shimmering effect with various shades of blue, green and purple. To complete the scene, some light pinks and purples could be used to create a soft, underwater atmosphere. With this color scheme, this grand palace could become an enchanted underwater oasis.