This is so cool, Dave! I am rather confused, I have to admit....:)
However, here's my go at it:
Image 1: Kasumi Pearls
Image 2: Sea of Cortez
Image 3: Mikimoto Akoyas
Image 4: Dyed black Akoyas
Image 5: Mixed Freshwater
Image 6: South Sea (golden and silver 50:50)
Image 7: Tahitian Peacocks...