For what it’s worth, I bought a second hand, no longer in production piece from an incredibly reputable source, only to have my previous SA tell me the same thing - that the serial number was bad, couldn’t be traced, blah blah blah. Turns out he was totally incorrect and was basically annoyed that I didn’t spend that money with him. I have not shopped with him since. I returned the necklace which was stupid and still a huge regret, but oh well. My point is, we can’t take our SA’s words as gospel.
@marbella8 is absolutely correct that an SO via in independent location wouldn’t show up - same as purchase history at an independent boutique. All of my SOs come from my home store which is independent / stand alone, so I would be curious to see what my serial numbers show up as if searched via a corporate location. I’m not saying that I have an opinion on this pendant one way or another. It’s a very “odd” combination that obviously isn’t on any SO spec sheet I’ve ever seen, but we all know that VVIPs get what they want. So who knows. I’d pay the $1800 if you love the piece to get a COA if it’s authentic.
ITA- most SAs don’t know much. A lot of us on here seem to know more than them. They work there for a year or 2 and don’t know vintage or SOs often. I think most don’t even know about the various stamps on a piece and their location, but they sure know how to have attitude and make you feel bad if you didn’t buy a piece through them, lol.
The VVIPs get prices made that are an absolute no for the VIPs.
If you got the piece at a decent discount, it’s worth paying the 1800 for authentication, since you’d be getting a SO that has a markup anyhow and maybe one you can’t even get approved right now. Best of luck and don’t stress about it. You got it from FP, and that is the best assurance that if it isn’t authentic, they’ll stand behind it.