Hi Jean,
I donīt think what you see is the nucleus but just another layer of conchiolin or the tiny platelets the industrial oyster puts on..
Perhaps it is the conchiolin as it has no luster, the platelets would probably show luster....
Lovely pearl and the idea with the golden starfish sound very great - wholly new design and if the pendant dangles or swings, sometimes the starfish can be seen, sometimes not!
