News: MED Merlin Diamonds Says Ore Processing Capacity To Double At Diamond Mine In Northern..., page-5

Merlin was not operational in the 80's, it was originally found by Ashton and was developed I believe in a joint venture with RIO, mining occurred around 1998-2003. The RIO takeover had more to do with Ashtons share of Argyle that DeBeers were trying to get hold of. There is not just two large pits, 9 or 10 of the pipes were mined. These pipes are considered small, narrow pipes, RIO actually took the easy stuff. So it is not considered low cost. This does not mean it cannot work but if it was easy it would have already been done.
Also what diamond mining did Joe do in the 80's, the only two Australian mines were Argyle and Bow river back then.
I hope this mine works it is good for the Australian diamond industry, but keep it real.