I guess I wasn't clear enough about this the first time. Minecraft Username: gobolts619 Reason: S/he was following me and one other player as we made a deal when I bought a diamond. S/he snuck up and stole the diamond and ran off. (Edit) After we told him or her to leave since she was following us, we ran around the spawn and even went to different places around the spawn to leave (spawn shop, mining world, etc.). This chase was about 10 minutes long, and I kept PMing eli_89_beard about this (look back at chat logs to see). After handing over the diamond when we thought gobolts was gone, s/he ran behind and took the diamond. I chased him/her around asking for it back, but they refused. I went everywhere, and even shouted. Counter-Reason: Evidence: ask the player eli_89_beard, he was part of the trade. PS: Sorry for the double post, I wasn't clear the first time I posted about this and forgot to delete it.
The user has been warned. In the future, you should probably just make a trade sign for the player to buy the item from, as that would make it easier. Sorry for the inconvenience.