I have an important question. Someone that I traded with has accused me of sending a fake card. The card is Goblin Lackey from Urza's Saga. I do not believe the card is fake, but I didn't test it before I sent it. ( I honestly didn't even know there was a test you can do.) He said that it fails the blacklight test. Does anyone know what this means? Anyway, I'm fairly new to the online trading thing, and I feel like maybe he's trying to scam me because he traded me something that went up in value after the trade was accepted.
My question is, what can I do to protect myself from another users accusations that I'm sending fake cards? If the card is actually fake (which I doubt), it was by no means intentional and I would gladly send him a replacement card. He suggested sending back all the cards that were traded to fix the issue, but I don't feel that's fair to me if the card is legitimate. Also, he only told me it was fake after I gave him positive feedback.
Any suggestions would be helpful.
(I'm mostly just venting my frustration because I don't know what to do.)