Is this a mikimoto necklace with pendant?

My grandmother recently passed, and apparently she was really into pearls. I found this necklace/choker in a Mikimoto, Ginza Tokyo bag in her hoard that I was curious about.

The necklace pearls are small, but very vibrant. The clasp though is very small and cylinder, and I had to look under a microscope and I can see a “M” and a 750 on it. It sort of looks like a “C” in front of the M, but I’m not sure. The pendant has a “SBN750” on it, so that seemed odd. She has so many pearl necklaces though that it’s possible things got mixed around and this necklace doesn’t go with the bag. It seems like a creative style, and is in really good shape otherwise, but no idea the brand or if it’s a real mikimoto necklace. Any help is appreciated.

Not Mikimoto...but that bag might have contained a small Mikimoto pendant necklace? Nice! European gold mark, so maybe a european maker? I would take it to a local jeweler to see what kind of stones those are in the pendant. Those are freshwater in the pendant so Not older than the 1990's. The value in this would be the design, gold, gems & pearls. Once you find out the gold karat & gems in the pendant... (plus the weight of the whole necklace) you can look on eBay for something similar with a good amount of gold in the pendant. (To be more accurate, you need to checkmark "solds" if it is for insurance.. gold is high right now.)