Above, my first attempt at emulating the coloration of the Beautiful Little Cowry. Several things are not right with it. Too much scattering of enamel, and two, color is off. Pretty clumsy effort.
There is also another difference between the two examples. The second is domed and I added some opalescent enamel to see if I could get it too look more like the natural glossiness of the cowry. Enameling is at first all about experimentation until you get the results you want. One thing about enameling is that you can add more color if you want. I'll have to decide if it's worth it or not.
I used Thompson enamel, 80 mesh, Foundation White for the base, Mocha Brown, Chamois Brown, and A3 Holding Agent.
These examples are torch fired, using a propane fueled torch. You can use a small butane torch if your piece is not too big. Pieces were placed on a wire mesh on a tripod, with the torch held underneath, about 3 inches below, and moved around. You have to watch that you don't over-fire the piece. One drawback of firing from underneath is fire scale on the back. You wait for the piece to cool and then pickle it to remove the fire scale. You can remove fire scale with PennyBrite and elbow grease, but pickle is better. If I were to follow a different method of firing, I could eliminate the fire scale altogether.
We have just had our first real winter storm here, and tomorrow is supposed to be cold, so I may not do anymore enameling. I do that out in the unheated garage.