You can turn around and resell a Banksy for something comparable to what you just paid.

Try doing that with a diamond. You walk out of the diamond showroom with it, and its resale value plummets to the value of the base metals, the work of the setting, plus a small fraction for what you had just paid for the diamond.

A certified laser etched diamond is a mass produced item that is pretty easy to authenticate. The brand name store selling it to you is invisible once it’s on your hand. There’s no such thing as a “used” diamond.

So the diamond is worth whatever it can be bought / sold for online. If walking out of the store drops it’s value, you’re donating to the store.

Buy an exactly equivalent stone elsewhere if the price drops too much after you buy it.

I think the issue is that there is no really trustworthy place to go for used diamonds to ensure you're not buying a cheap knock-off or lower grade gem. Most people don't understand cut, clarity, and whatever else are the other ones. Pawn shops are amazing places to buy SUPER cheap jewelry, especially diamonds. The issue is that, unless you definitely know what you're doing, it's super easy to get taken advantage of.

I wish there was a trustworthy clearinghouse/reseller for used jewelry and gemstones. That would be fantastic.

Given that NFTs are a scam that only exist to make fraudsters rich while helping pollute the planet, I would take the JPG every hour of every day.

I'll take the NFT.

The NFT is a pointer to the image, not the image itself. Owning a copy of the JPG is actually closer to owning the art.

JPG of a Banksy