There are many ways to add color to the tail and fin of your polymer clay mermaid sculpt. One very easy way is by painting with heat-set or acrylic paints. Another way is to add a very thin layer of a polymer clay in a color you like. You can also add a thin layer of a liquid clay. And don't forget that glitter is often sprinkled onto the tail to add sparkle. This doll maker shares his method of 'painting' a mermaid tail using embossing powder in a photo tutorial:
The fin part of the tail can be made from polymer clay or other materials. Thanks to this doll maker for some photos of fins she made using Angelina and Fantasy Films:
See more about sculpting a mermaid in in this blog's Index under 'Fantasy- Fins and Tails'