ramu comparison, page-3

As far as I am aware cut-off grade refers to the grade threshold above which they calculate the resource. The inference is that grades lower than this are probably not economic. For example the whole wowo area may contain twice as much Nickel if you used a lower cutoff of 0.5%. But that sort of statement is a bit meaningless if grades of 0.5% are not economic.

Having said that, the higher the price of the commodity - in this case Nickel, the more economic lower grades become. Therefore the total resource increases.

This is exactly what happened with PDN and the surging Uranium prices...