The new shell with blister is in hand. The blister is located in the final body chamber of a mature Nautilus, so it would have had a period of up to several years in which to form. I will be taking it to Peter Ward at the University of Washington for X-Ray and for his opinion regarding its potential for shedding light on biomineralization in the posterior (dorsal) Nautilus mantle.
Now let's circle back to a pivotal moment in this thread, about halfway through to this point:
Separation of pearl and shell at origin was an unfortunate decision, however if the pearl were determined to be a blister pearl and not a fully formed pearl with a conveniently-photogenic attachment point, arguments would be strong in favor of authenticity. However, upon what now appears to have been an informal initial examination, GIA's Ken Scarratt determined that it was a button pearl with superficial attachment—not nearly as conclusive.
We have just received GIA certificates with their official reports on quite a number of the pearls shown throughout this thread. That particular pearl has come back as 'NATURAL BLISTER PEARL, SALTWATER, SPECIES UNDETERMINED' (can’t blame them for cold feet at this point!).
This result gives added weight to my more recent post:
Below are pearls from prior posts that most strongly come to mind when I think of Nautilus pearls. Top row is the infamous pearl reportedly found attached to a dry shell last November…
All shown pearls certified as natural saltwater, species 'undetermined.'