Diamond appeared before the independent disciplinary panel and admitted the breach of RFU Rule 5.12 – conduct prejudicial to the interests of the game and/or Union.
In summary, Sam Hillas KC, the chair of the disciplinary panel described Diamond’s behaviour as “wholly unacceptable”.
Hillas said: “The language used was inappropriate, abusive and entirely contrary to rugby’s core values.
“There is no place for abuse of match officials and this applies with equal force whether dealing with the professional or community game.”
The panel deemed a six-match suspension to be a “proportionate” sanction.
In his post-match interview following the game at Sandy Park, Diamond admitted he was annoyed with the officials, telling BBC Radio Newcastle: “Like the first game up in Newcastle it was a close game – this one was decided by the officials.
“There was a clear act of foul play in the try and I don’t know for the life of me why the VAR man doesn’t have a look at it at least.”
Newcastle are bottom of the Premiership and next host Northampton Saints at home on 18 April, before games against Bath and Saracens away, Gloucester at home and Leicester Tigers away on the final day of the campaign.
