@Derndeff Anyone who doesn't have an emerald/diamond exchange system through villagers should not trust using emeralds as a valued currency. (and players will not trust this. I won't, anyway) One way you could fix this is by having an emerald/diamond exchange system that is static, either done at spawn or by a trusted player.
But then you have the exact same issue. An emerald is just a diamond, and diamonds have a seemingly unstable value. (or at least that's the argument, right?)
Anyway, if you believe heavily in the emerald system, why don't you start selling items for emeralds? You know roughly what they're worth, so why not start using it as a currency?
What is with you guys so desperately wanting a villager trade for emeralds to diamonds! It's never going to happen again! There's no need for it.
If you haven't been listening, an emerald is NOT "just a diamond." They are completely different. It's comparing a dollar bill to a diamond ring. They are NOT the same. Emeralds are the official minecraft currency for in game use, but people don't like using them cause they apparently can't grow crops and go to spawn to sell them for limitless amounts of cash. All the people that complain about not having access to emeralds should really check out the trading post. There are villagers there that you can trade stuff with, like crops, which you can grow very easily and in mass quantity if you work for it. There you go. Emeralds for days! (btw, the unstable part is not the argument here. It's wanting to switch from diamond use to primarily emerald use and the arguments for/against that. The economy will always shift around. And this one is still new, so prices haven't settled yet even for diamonds because we are still getting over what prices were like before reset when diamonds weren't as valuable. They are unstable because we are still figuring out what they are worth.)
This emerald/diamonds exchange system through villagers isn't going to happen. It can't unless we wanna live in a place where diamonds can literally be thrown away and no one will bat an eye about it, because that's what happened before reset. Everyone converted every emerald they had into diamonds and diamonds became super inflated. People scrambled to make emeralds then, cause they could buy their expensive jewelry with it. But now we've taken away your jewelry store and are asking you to pay in cash. It's tough, I get it. I was in favor of keeping the custom villagers myself. But we don't have that now and we shouldn't have it. It'll be abused by diamond horders who only hurt the economy.
And what is this apparent issue of trust? Did you get scammed or something? Cause the people I know are trustworthy. Even the raiders and people I would never play alongside in game I am freely willing to trade with because in trading they are honest people who price things for what they are worth. The only issue is that raiders and griefers rarely do anything besides destroy, so they often don't have a desire to earn emeralds through farming or vanilla villager trading, so they'll probably still pay in diamond until they start stealing emeralds too.
And once we do establish how much an emerald is worth for different items, there will be a monopoly unless other shops follow suit in the conversion. This then makes more shops convert to emerald trades and match the prices of other shops, creating a competitive economy based on emeralds for basic items. All it takes is a few people to open shops, even temporary shops, in order to start the movement.