Thanks for posting more photos! I strongly believe these are Akoya pearls, and you could be spending hundreds of dollars needlessly to have them x-rayed.
The pearls appear solidly opaque, and "machine-turned." I don't mean this literally, but it is a term I use in the attempt to describe the difference between natural and cultured pearls.
Also, the knots between the pearls are fat and appear like thick twine. Natural pearls were sold by weight -- not diameter, as with cultured pearls -- so the drill holes were almost always (never say "always" in anything related to pearls!) made as small as possible to minimize weight loss, and would not accommodate thick thread. I've had natural pearl necklaces that were badly overknotted, but always on fine silk.
If you want a proper written appraisal, it's normal practice to leave a piece for one to three weeks. I wouldn't worry about this, unless you have some specific reason to distrust the jeweler, in which case I would take it somewhere else.
The pearls appear solidly opaque, and "machine-turned." I don't mean this literally, but it is a term I use in the attempt to describe the difference between natural and cultured pearls.
Also, the knots between the pearls are fat and appear like thick twine. Natural pearls were sold by weight -- not diameter, as with cultured pearls -- so the drill holes were almost always (never say "always" in anything related to pearls!) made as small as possible to minimize weight loss, and would not accommodate thick thread. I've had natural pearl necklaces that were badly overknotted, but always on fine silk.
If you want a proper written appraisal, it's normal practice to leave a piece for one to three weeks. I wouldn't worry about this, unless you have some specific reason to distrust the jeweler, in which case I would take it somewhere else.