How do I figure rough cost?
The basic rule of thumb for figuring rough cost is that there are five carats
in a gram and if you figure an average finished yield of 30%. Then for every
gram the rough weighs you will get 1.5 carats per gram finished cut stone
If I am not sure how the rough will yield I figure 20% to be on the safe
side. Which is 1 carat per gram of rough.
Remember the yield will go up as the stones get larger, and some materials
like Tourmaline in an emerald cut will yield much better than 30%. So these
are just estimates.
For example, you are cutting a piece of Tourmaline that you paid
$8 per carat for rough, and the rough/stone weighs 10 cts, it cost you $80.00
for the rough. Your finished stone will be 3 carats (30% yield, if you do
not have any problems). So $80.00 cost / 3 carats = $26.66 per carat, this
is your finished cost per carat.
A down and dirty, quick easy way to figure yields (on the conservative side)
is to figure the yield at 1 finished carat per gram (20% yield).
This method is easy to use because you just figure 1 carat per gram of rough
weight. If a piece of rough costs you $40.00 per gram rough, then your finished
cost is $40.00 carat.
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