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- diamond
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diamond cutting
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What is diamond cutting?
Diamond cutting is a specialized art involving five steps: marking, cleaving, sawing, girdling, and faceting. Marking involves deciding how to cut the diamond for the greatest value, considering its shape, imperfections, and crystal grain. Sawing uses a thin, diamond-dust-charged blade to cut the diamond. Faceting involves creating the diamond's facets (flat surfaces). The brilliant cut is a popular method that maximizes the gem's fire and brilliance through precise angles and proportions. A standard brilliant cut has 58 facets.
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Why do diamonds need to be cut and shaped?
Diamonds are cut and shaped to maximize their brilliance and fire. The process involves several steps, beginning with marking to determine the optimal cut for the greatest value, considering the diamond's shape, imperfections, and cleavage. If needed, the diamond is cleaved to preshape it. Following this, the diamond goes to a lapper, who places the first 18 facets. Then, a brillianteer adds and polishes the remaining facets to achieve the standard 58-facet brilliant cut. The angles and sizes of these facets must be exact to yield maximum brilliancy and symmetry.
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What tools are used in diamond cutting?
Diamond cutting involves several tools at different stages. Large diamonds are often cleaved with a steel wedge and mallet after a groove is cut with another diamond. Saws with diamond-dust-charged, paper-thin phosphor bronze disks are used to saw the diamond. The diamond is mounted in a dop and clamped so that it rests on the blade while the sawyer operates the machinery. Diamonds are also used in machine tools for cutting applications, such as taking light finishing cuts at high speeds on hard or abrasive materials and for finish-boring bronze and babbitt-metal bearings.
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What are the basic steps in the diamond cutting process?
The diamond cutting process involves several key steps to transform a rough diamond into a polished gem.
- Marking: Each rough diamond is examined to determine how it can be cut to maximize its value, considering its shape, imperfections, and cleavage direction.
- Cleaving: If necessary, large diamonds are pre-shaped by cleaving them into suitable pieces for sawing. The cleaver makes a groove along the marked line and uses a steel wedge and mallet to split the diamond.
- Sawing: If cleaving is unnecessary, sawing is the second step. A paper-thin disk of phosphor bronze, rotating at 4,000 revolutions per minute, cuts the diamond. The saw's rim is charged with diamond dust to facilitate the cutting.
- Faceting: The diamond goes to a lapper, or blocker, who places the first 18 main facets. Then, a brillianteer places and polishes the remaining 40 facets, if the stone is being cut in the standard 58-facet brilliant cut.
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How do diamond cutters decide what shape to cut a diamond into?
Diamond cutters decide the shape of a diamond based on several factors to maximize its value. They consider the rough diamond's shape, as well as the number and location of imperfections. It is important to determine the direction of the cleavage, or grain, within the diamond crystal because diamonds can be cleaved in four directions. The planner marks the diamond to indicate where it should be cleaved or sawed.
The most popular cut style is the brilliant cut, a round stone with 58 facets. Any style of diamond cutting other than the round brilliant or single cuts is called a fancy cut, or fancy shape; important fancy cuts include the marquise, emerald, oval, baguette, heart shape, pear shape, kite, triangle, and trilliant.
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How does diamond cutting affect a diamond’s value and appearance?
Diamond cutting significantly influences a diamond's value and appearance. The process begins with marking the rough diamond to determine the optimal cut for maximum value, considering shape, imperfections, and crystal grain.
Faceting, especially in the popular brilliant cut, involves creating precise angles and symmetry to maximize brilliance and fire. A brilliant-cut diamond has 58 facets, with specific angles for the crown (35°) and pavilion (41°) to reflect light effectively. Skillful faceting is essential because correct facet angles yield maximum brilliance, and accurate sizes maintain symmetry. Other styles, known as fancy cuts, include marquise, emerald, and heart shapes.
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diamond cutting, separate and special branch of lapidary art involving five basic steps in fashioning a diamond: marking, cleaving, sawing, girdling, and faceting.
Marking
Marking is done after examining each rough diamond to decide how it should be cut to yield the greatest value. To make this decision, the shape of the rough diamond and the number and location of imperfections must be considered. Of utmost importance is the determination of the direction of the cleavage, or grain, in the diamond crystal (because of its atomic structure, diamond can be cleaved in four directions parallel to the octahedron crystal faces). Taking these factors into account, the planner decides how the diamond should be cut and marks it to indicate where the stone should be cleaved or sawed.
Cleaving
If the planner’s decision is to cleave the stone, it then goes to the cleaver. Large diamonds are often preshaped by cleaving into pieces suitable for sawing. When the stone is very large and valuable, the cleaving is a most critical process, because a mistake by the planner or the cleaver can shatter the stone. The cleaver cuts a groove along the line showing where the stone is to be cleaved, using another diamond as a cutting tool. He mounts the diamond in a holder called a dop and inserts a steel wedge into the groove. He strikes the wedge sharply with a mallet and the diamond splits along its cleavage.
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Sawing
The third step, or the second step if cleaving is unnecessary, in the diamond-cutting process is sawing. The saw is a paper-thin disk of phosphor bronze, rotated on a horizontal spindle at about 4,000 revolutions per minute. The sawyer mounts the diamond in a dop and clamps it so that it rests on top of the blade. The rim of the saw is charged with diamond dust, and, as the sawing progresses, the blade continues to recharge itself with diamond from the crystal being cut. The saw will cut through a 1-carat rough diamond in four to eight hours, unless it strikes a knot, in which case it may take much longer.
Girdling
The next step in cutting a round stone is called girdling (rounding; bruting). The diamond to be girdled is placed in the chuck of a lathe; while it spins, a second diamond mounted in a dop on the end of a long handle is held against it, and the diamond is slowly rounded into a cone shape. Some fancy-cut stones are girdled by mounting them off-centre in the lathe chuck.
Faceting
From the girdler the diamond goes to the lapper, or blocker, who specializes in placing the first 18 main facets on a brilliant-cut diamond. It then goes to the brillianteer, the worker who places and polishes the remaining 40 facets, if the stone is being cut in the standard 58-facet brilliant cut. Placing and polishing are done by setting the stone either in a lead dop or a mechanical clamp and holding it down on a revolving cast-iron lap (horizontal, circular disk) that has been charged with diamond dust. Great skill is necessary at every stage, but especially during faceting, because the angles of the facets must be exact in order to yield maximum brilliancy, and their sizes must be accurately regulated to preserve symmetry.
The most popular style of cut is the brilliant cut, a round stone with 58 facets. A single cut is a simple form of cutting a round diamond with only 18 facets. Any style of diamond cutting other than the round brilliant or single cuts is called a fancy cut, or fancy shape; important fancy cuts include the marquise, emerald, oval, baguette, heart shape, pear shape, kite, triangle, and trilliant. The term melee is used to describe smaller brilliant-cut diamonds as well as all small diamonds that are used in embellishing mountings for larger gems.
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