RE: Calling Rockingeorockingeo,
thanks for your post outlining the impact of crystal (habit) shape on rough stone valuations..... I have taken the liberty of posting it on the SL board where a similar post about rough diamond valuation was made recently by Heavymoney.... see below
|  If someone would offer us a 5 carats rough diamond, for example, stone structure, VS2 and G colour. |
| | The stone structure we will yield approximately 50 percent of the finished diamond:
5 carats (rough) x 0.50 (50 %) = 2.50 carats (polished). |
| | If we decide to cut the octahedron in half to yield two equal finished stones:
2.50 carats ÷ 2 = 1.25 carat (for each polished diamond). |
| | The Rapaport value for a 1.25 carat, VS2, and G colour is US$2,500/carat:
2,500 x 1.25 = US$3,125 (for each stone). |
| | This type of stone will yield 2 X 1.25 carat stones:
US$6,250 (3,125 x 2). |
| | We will discount the Rapaport value by 40 percent to obtain the wholesale market price:
1.25 x 2,500 x 0.60 (- 40 %) = US$1,875 (for one diamond), total US$3,750 (for two polished diamonds). |
| | To obtain our purchase price for this rough diamond of 5 carats, it is necessary to apply a percentage which will correspond to our profit margin (on average it is best at 50%):
3,750 x 0.50 = US$1,875 (this is our purchase price for this rough diamond). |
| | The purchase price per carat for this rough diamond is:
1,875 ÷ 5 carats = US$375 per carat. |