Friend cant see purple diamond

[Tannen]

A friend of mine apparently cannot see the purple diamonds by the hp bars that show experience range. It seems this has always been the case with him, since he was clueless about what they were. He has a bunch of mods installed though, so I was wondering if theres any known issue with some mod and the purple diamond?

Unless its a bug or something.

[Drakinho]

You can enable/disable seeing them in your options menu.
There's a good chance your friend simply didn't tick that box.

Otherwise, mods can always be at fault for everything (True Story), try to remove them in case the box was ticked.