Sea shells are simply gorgeous freshly plucked from the sand. But once dried the color fades quickly. You may also find that some shells hold a smell to them, even from the tiniest bit of protein left on their surfaces.
There are a few ways you can clean your seashells to prevent them from smelling. If there is a good bit of meat on the shells, place them next to an anthill in your yard. After a few days you will find the ants have wiped the shell clean! Then, place your shell in water with a few tablespoons of bleach added to the mix. You can also use vinegar and water to clean and remove smells.
Once your shell is clean and fresh smelling, let it dry completely. Then you can make your seashell shiny by using one of two methods. First, if you have a Dremel, purchase a polishing bit and buff the shell with the Dremel. The second sea shell polishing method is to wipe down the shell with mineral oil. This method makes the shell colors stand out, however you will probably have to reapply the oil every few months.