Ann: 5N HPA Production Confirmed, page-20

Further to the above Toolbarismint., The production of HPA to a 4N state is the sweet spot economically. It is far and away cheaper to produce, and there is significaly less loss of AL2O3 throughout the processes., And there's multiple markets to sell the end product into.

The only Comapny that will be mass producing 5N HPA is A4N. They however will be doing so to feed their own in-house processes for the of manufacturing of Sapphire Glass. This sells at around a Million Dollars per Tonne! This will account for near half their annual production capacity.