.
A new name to me too.
Black Knights, Black Arrows, Redskins, Blue Diamonds, Red Pelicans, Yellowjacks, Red Arrows and even the Blue Chips, but I hadn't until now heard of the Black Diamonds.
The only trace I can find is the RAAF team which flew Sabres in the 60s.
Was it an official RAF name?
Or an informal team tribute to their leader, Sqn Ldr (George) Black?