keep in mind that only 2/3 of the concentrate goes to SRC, the other 1/3 to DeBeers lab in SA... which is also no charge.
Of the 1500kg of material SRC only recieved 1050 kg, also the rates for larger sample go down....
In any case the rates are the rates..... if one is going to take a bulk sample the cost of processing it should not be a deturent. Either the diamonds are there of they are not, and processing the sample is the only way to find out if the grade and value are suffecient to support a mine.....
What would be the point of exploring if you're not prepared to pay for lab costs.