Diamond cutting
From Wikipedia, the free encyclopedia
Diamond cutting is the art, skill and, increasingly, science of changing a diamond from a rough stone into a faceted gem. Diamond cutting requires specialized knowledge, tools, equipment, and techniques because of its extreme hardness.
'Cut' has two meanings in relation to diamonds. The first is the shape: round, oval and so on. The second relates to the specific quality of cut within the shape and the quality and price will vary very greatly based on the cut quality.
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[edit] Diamond cutting process
The diamond cutting process includes these steps; planning, cleaving or sawing, bruting, polishing, and final inspection.[1]
[edit] Planning
Diamond manufacturers analyse diamond rough from an economic perspective, with two objectives steering decisions made about how a faceted diamond will be cut. The first objective is that of maximum return on investment for the piece of diamond rough. The second is how quickly the finished diamond can be sold.
[edit] Maximizing Value
The process of maximising the value of finished diamonds, from a rough diamond into a polished gemstone, is both an art and a science. The choice of cut is influenced by many factors. Market factors include the exponential increase in value of diamonds as weight increases, referred to as weight retention, and the popularity of certain shapes amongst consumers. Physical factors include the original shape of the rough stone, and location of the inclusions and flaws to be eliminated. Maximizing the value the value of a rough diamond is carried out analysing these these considerations for the best choice.
[edit] Weight retention
The weight retention analysis studies the diamond rough to find the best combination of finished stones as it relates to per carat value. For instance a 2.20ct octahedron may produce either two half carat diamonds whose combined value may be higher than that of a .80ct diamond and .30ct diamond that could be cut from the same rough diamond.
The round brilliant cut, or square brilliant cuts are preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals such as macles are more likely to be cut in a fancy cut—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.
Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight; rarely is it less than 50%.[citation needed] Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the carat rating. Since the per carat price of diamond shifts around key milestones (such as 1.00 carat), many one-carat diamonds are the result of compromising Cut quality for Carat weight. Some jewelry experts advise consumers to buy a 0.99 carat diamond for its better price or buy a 1.10 carat diamond for its better cut, avoiding a 1.00 carat diamond which is more likely to be a poorly cut stone.
[edit] Color retention
In colored diamonds, cutting can influence the color grade of the diamond, thereby raising it's value. Certain cut shapes are used to intensify the color of the diamond. The radiant cut is an example of this type of cut.
Natural green color diamonds most often have merely a surface coloration caused by natural irradiation, which does not extend through the stone. For this reason green diamonds are cut with significant portions of the original rough diamonds surface (naturals) left on the finished gem. It is these naturals that provide the color to the diamond.
[edit] Turnaround Minimization
The other consideration of diamond planning is how quickly a diamond will sell. This consideration is often unique to the type of manufacturer. While a certain cutting plan may yield a better value, a different plan may yield diamonds that will sell sooner, and thereby returning the investment sooner.
[edit] Cleaving or sawing
Cleaving is the separation of a piece of diamond rough into separate pieces, to be finished as separate gems.
Sawing is the usage of a diamond saw, or laser to cut the diamond rough into separate pieces.
[edit] Bruting
Bruting is the process whereby two diamonds are set onto spinning axles turning in opposite directions, which are then set to grind against each other to shape each diamond into a round shape. This can also be known as girdling.
[edit] Polishing
Polishing is the name given to process whereby the facets are cut onto the diamond, and final polishing is performed. The process takes the steps; blocking, faceting, and polishing.
[edit] Final inspection
The final stage involves thoroughly cleaning the diamond in acids, and examining the diamond to see whether it meets the quality standards of the manufacturer.
[edit] Cutting process
It is possible only because the hardness of diamond varies widely according to the direction in which one is trying to cut or grind.
[edit] See also
[edit] External links
- Diamond Design, Marcel Tolkowsky. Web edition as edited by Jasper Paulsen.
- Editor's notes 41-45 link to ongoing diamond cut research.
[edit] References
- ^ Diamonds and Diamond Grading: The Evolution of Diamond Cutting Gemological Institute of America, Carlsbad, California, 2002
