This February, we were offered a very nice parcel of Botswanan rough. The size of the stones ranged from 2.60 up to 4.60 Carats, 42 stones in total. With most of the stones being makeables, thus returning only one polished stone, we were looking at the possibility of cutting about 42 stones with a finished weight between 0.70 and 1.75 Cts.
The colour of the stones was very hard to estimate, since the rough seemed to have a lot of colour in the surface. Talking to other cutters, we learned that this is normal with rough from Botswana. However, we tried to estimate the exact colour of the stones. If we would give a D colour the value of 1, E the value of 2, and so on, up to J the value of 7, we estimated an average colour of this parcel of 4.58, or an average of G-H in colour.
These stones also contained a lot of naat, and inclusions, which were difficult to judge, and we estimated the average clarity of the parcel as SI1. Figure-wise, with IF being 1, VVS1 being 2, and so on, we thus estimated this parcel at an average clarity of 6.
Quickly estimating the weight of each finished stone gave us a final estimated weight of 47.90 Carats, thus a yield of 34.65% from the rough.