me coding_j got banned!?

First of all, we never ban player for unknown reason. The reason is clearly stated in the ban message, you were banned for xray.

You and SoggyAsparagus mined together. SoggyAsparagus made most of the tunnels, while you mined most of the diamonds.
At almost every diamond patch, you mined the ores a few seconds after him uncover them. I would say there is no way you didn't know he was xraying.
Even if you don't use xray yourself, there should ring a bell when the mines looks like this, and he uncovers diamonds in every corner and bend:




Here is a short video of where some of the diamond ores were found:




You both are welcome back after 7 days, without cheats.

Have a nice day.