This is a conjoined pearl, not a blister. Blister pearls are given rise by external factors, where this pearl is internal in onset. It was likely a single pearl which irrupted from it's sac, later to become affixed to the shell within the extrapallial space. As Jeremy suggested, a pearl which has been cut from a shell greatly loses value, if not destroyed. A good crafter may do well to hide the cuts beneath the setting to add some value. However, this is not the only issue.
Currently, seven giant clam species are candidate species for listing under the Endangered Species Act
. This includes two species in the genus Hippopus
and H. porcellanus
) and five species in the genus Tridacna (T. derasa
, T. gigas
, T. mbalavuana (tevoroa)
, T. squamosa
, and T. squamosina (costata)
. Uncertified trade in Giant Clam products is prohibited in North America. It is only permitted when it's proven to be reared and harvested in a sustainable manner.
Pearls from giant clams have little or no scientific value, after all they are widely known and largely understood how they form. Some loose pearls from Tridacna sp. present with alluring patterns and are quite collectible, but ethically dubious at the same time. If you were to send it to the GIA in any form, they would return it, untested. Not just because it is from an endangered source, but also because the species is already known and not questioned.
As gemstones, they are low to moderately nacreous, unlike the highly nacreous pearls from traditional oysters and mussels.
I'm sorry to disappoint, but your best action is to do nothing. Keep it as a collectible, a curiosity and conversation piece.