As a test, I tried to edit a moderator diamond into my name and got this error message:
Oops! There was a problem updating your profile:
- Display Name can only contain a-z, 0-9, spaces, apostrophes or hyphens and must start with a letter or number
I trusted what it said, until Michael Mrozek pointed out the comments of Should psi be a reserved character for usernames to prevent impersonation? that it isn't correct; for example, non-Latin letters are allowed. This message should be updated to correctly reflect what is allowed in a display name.