Vintage JLC. Gold plated? Authentic?

I've been offered the possibility to swap a watch of mine for this vintage jlc 36mm which is claimed to be authentic and gold plated.

However, I'd like to hear an experts opinion about it. I mean, the caliber should bear cotes de geneve, don't you think? And I'm not quite convinced overall, sicne I don't know the seller.
What do you guys think?

Thanks in advance.

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