No comment on pearls - I can't see much detail other than a couple of livable blemishes and know little about SSP, definitely not nearly enough to approximate quality from given data.
The clasp though... looks pretty good. Despite the difference of 'visible' properties (RI, color etc.), topaz and aquamarine are not that easy to tell apart off hand especially when the colors overlap as it is in this case. In person, something gives aquamarine away most of the time - inclusions, a bit of greenish tint or subtle zoning... things that topaz wouldn't have. Some of the time, it is a pretty good 'personality test' to give someone particularly tricky topaz and aqua and ask 'what is it' - it is supposed to be no brainer easy on paper, but it isn't
Now, the emerald cut is way more common for aquamarine, as is a fairly fancy platinum setting. Would rather believe the seller. besides, the stone is not huge and not very deeply colored, so its contribution to the overall cost shouldn't be anything to write home about whichever way.
Just an opinion, and some detail about what it is based on. Hope it helps
The pearls are quite intriguing for starters. I hope this thread will continue with something more useful about the main subject - the pearls, that is.