(Edit/add: Though, contradicting my own argument a bit, I think point 2 and 4 - that there was deliberate effort to establish it as a "luxury item" and that today it's used to fund all kinds of atrocities - could be able to change demand of diamonds: They also change the things that wearing a diamond would imply about the wearer.
The Mossanite argument makes no sense because one of the points of wearing a diamond is to be seen as "my significant other is rich and/or dedicated enough to gift me this" - however, no-one wants to be seen as a helpless brainwashed sheep or a supporter of war crimes.)
Even if she doesn't leave you over this, unless you somehow married a Hackernews you've set up the image in her head that you're a skinflint who isn't willing to provide for your wife and it will affect your relationship in negative ways. Is your autism that strong that you will put a pedantic commitment to your own head logic and fighting the evil forces of marketing above your wife's feelings? If so, maybe you don't deserve to be married.