SITHY GEMS LAPIDARY - Sri Lanka
How TO EVALUATE YIELD RECOVERY FROM ROUGH GEMSTONES
Following information will give you just an idea what to expect from the gemcutter AFTER FINISHED CUTTING THEM.
a) HIGH QUALITY CUSTOM CUTTING : Yield Recovery of 20% - 45%
c) UPPER COMMERCIAL GEM CUTTING : Yield Recovery of 15% - 20%
d) LOWER COMMERCIAL GEM CUTTING: Yield Recovery of 3% - 15%
Above mention facts written based on experience of cutting stones, Yield of Gemstones based on the color, clarity, size/shapes & cuts. Step cuts always yield more weight than other cuts.
In Gemstones people look for color before anything.If you have the right color(AAA )for its kind ( species ), its more money. The Gemstone need to be oriented, to look good face up without impefection. Color of the gemstone need to be even through the table of Faceted stone (face-up). Most of the time, wastage of rough is higher when seeking for better color... but in other hand you will have a nice gemstones with good color, ( not a cheap color gemstone ).
Clarity / Inclusions )
Clarity plays a big roll on Gemstone appearence ( beside Transparent, Translucent, Semi-translucent or Opaque ) Some stones are accepted with certain type of inclusion (flaws) some are not. Gem-Cutters always need to look for accpetable inclusion, which will not threaten the durability of the gemstones or the beauty, Gemstones with certain type of inclusion.... need to be removed by triming or by laping............in this process vast amount of weight we could loose. ( before making a cutting decision gem-cutter need to decide the type of rough gemstones he is going to work on it, (1) is it facet grade rough ? (2) is buff-top or Cabochon Grade rough ? (3) is it Briolette or Bead Grade rough ? (4) finally its Carving Grade rough ?
If cutter cuts the stones as per the size & shape of the rough gemstone, yield recovery will be higher, if cutter force the stones to standard shapes & standard sizes yield rate will drops down. If rough stones are too flat & shallow yield rate & the size will drop down.
Cutting Basic Step-cut, yields more than Artisticuts. More work, .. more waste on the rough gemstone. If you cut "step-cuts" as per the shape & sizes of the stones could yield more (could retain more weight), if we cut checker board type of cuts and buff-top cuts could yield more too. .
Hope above mentioned information will guide you and give you an idea what you could expect from your rough gemstones.
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