Ann: Investor Webinar Presentation, page-67

Matt I'm sure you have quoted these amounts required before, now I will state that I am not a Geo you may be?
Your numbers look way to generalised as given the types of diamonds and the values you should be comparing to the most similar mines.
I would suggest Letseng and Karowe as both produce high value type 2 stones and have a high overall price per carat.
Letseng approximately has a surface area under 20Ha and a diamond grade of around 2ct per hundred tonne.
Karowe approximately has a surface area less than 5Ha and 14ct per hundred tonne.
On top of all this kimberlites are not uniform in shape below the surface and can be larger at depth.
Overburden and weathering have an impact.