Polishing a Diamond: Cost

Goals

To determine the price and the process for cutting and polishing a diamond.

Early Findings

There are five stages to diamond cutting and polishing.

Planning the cut of the rough diamond

  • This step usually involves figuring out "the best possible shapes of the diamond in order to minimize waste and maximize the yield of the rough stone."
  • Usually, the process involves the use of specialized programs like a Sarine machine.

Cleaving/sawing a rough diamond

Mechanical Bruting

  • The next step involves making the separate rough diamonds round. The process is called girdling.
  • In order to that, two rough diamond pieces are put across of each other and turned in opposite directions.

Polishing

  • The polishing process mainly involves creating the diamond's facets, which includes the use of a tang and a scaife.
  • The process is further divided into blocking and brillianteering.
  • In the blocking steps, "8 pavilion mains, 8 crowns, 1 culet, and 1 table facet are added to make a single cut stone" which serve as a template for the brillianteering step.
  • The brillianteering step adds "the remaining facets, bringing it to a total of 57 facets." This is probably the most important step in the whole process as it determines the diamond' fire and brilliance.

Inspecting the Polished Diamond

Pricing

  • Mercury Diamond is a "diamond pricing consultancy founded by Ehud Laniado" that features more than 18,000 prices for polishing and cutting a diamond.
  • The cost of polishing a diamond varies based on its color (from D to M), clarity (from SI2 to IF), and the shape (round, semi-round, or square).
  • For instance, diamonds between 10 and 15 carats that are SI2 cost between $8,300 and $30,400 per carat to polish while those that IF, or internally flawless, cost between $13,900 and $113,800 per carat to polish.
  • The polishing prices for 15 to 20 carat diamonds are similar to the 10-15 carat ones, with SI2 diamonds costing between $10,300 and $37,900 per carat while the IF diamonds cost between $16,700 and $122,500 per carat.

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