That is not quite how it works, statistically speaking - you just need each sample taken to be large enough to be representative of the overall. Then your samples have to be adequately spaced to pick up variation from location to location to give adequate estimation certainty.
Interestingly (very much so actually, it tells a very important thing) Mustang seem to have decided an auger (appears to be 50cm) is sufficient - they would have got advice on this up front for sure.
This indicates rubies are everywhere, if they we only getting one per auger point then statistically that would give much too low confidence to use in a meaningful estimate over a larger area.
I am guessing they are getting, at very absolute least, dozens of stones per auger point where they are concentrated. Obviously some auger points probably yield zero stones, but that is how you delineate the deposit edges.
I have some background here, I used to crunch resource numbers using Surpac and by hand, and also custom software that I wrote, some years ago when I was younger.
