Shiva Eye Operculum is harvested from shells in the Indian Ocean, Pacific Ocean, and the China Sea. Similar ones from the Mediterranean Sea are called "The Eye of Saint Lucia" and are much different than the warm water Operculum and come from a shell called 'Mediterranean Rough Turbo'

The two types are very easy to tell apart: 
The Mediterranean Sea Operculum are white on one side with a spiral and have an orange brown color on the opposite side. Fishermen collect the Mediterranean Rough Turbo shell, remove the Operculum then release the shell back into the waters where it will regenerate a new Operculum. These are more expensive.
 
The Indian Ocean, Pacific Ocean, and the China Sea (warm water) Shiva's Eye are harvested from different types of shells. They are white on one side with a more rounded spiral and the other side is dark brown, light orange, or dark blue to green.

The spiral on the one side is directly linked to the color of the other side on both types. 
 
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* Photos show both sides.
* Sizes, shapes and colors my vary due to being a natural stone, being hand-carved and/or difference in computer monitors.