Blue Coral 10mmSky blue colors throughout this stone that is fossilized coral. Blue Coral is also known as Sponge Coral because it contains so many tiny holes on its surface. Its color comes from iron salts in the water. Blue Coral comes from the tropics of the Indian and Pacific oceans. It is unique because this is the only naturally coral in the color blue. Blue Coral is so rare they haven't changed in their form for over 60 70 million years. It is a phenomenal,