That’s not what he said; he said keep the parts and file a CC dispute to get your money back.
What you said and what he suggested are two totally different scenarios; what you said is debatable and dependent on several factors. What he suggested to do is intentional, deceptive, and fraudulent.
Also, transactions are usually governed by the seller’s terms. Usually most retail transactions have fine print that by accepting the charge, you are agreeing to the terms of the sale. If buyer pays return shipping is one of their terms, then it’s on you to do so to get your cash back. Usually, sellers of any merit will give you an RA and pay return shipping, yet it’s still on you 100% to take your time, money, and resources to get to the post office/ups/whatever to ship it back. This is typical of many sellers, but there are exceptions. But if you are in violation of the sellers terms . . . It’s on you.
In your gold ring example, you may just be right, that you could keep the incorrectedly sized ring (or the correctly sized ring, for that matter.. hell) , and simply file a CC dispute. And you very well *could* be granted your dispute, keeping both the ring and your money. Eventually, the CC company will catch on due to multiple vendors reporting that your dispute is fraudulent, and they will no longer grant you CC disputes. So when you actually get shafted for real, it’s with no lube.
As i said earlier, OP got it right. Just cancel the order and get your money back if you don’t like the business practice. No need to be a slimeball