Selling Diamonds

(via Diamond Promotion Service) 31. Cleaving. When a rough diamond is to be divided ‘with the grain’, it is cleaved. The cleaver sets the stone in a dop, or holder, and he uses another diamond to scratch a groove along the division line. Then he inserts a square-edged knife into the groove and taps it back sharply with a mallet. If everything is right, the stone splits cleanly. If the division line has not been placed properly (or followed accurately), the diamond can shatter.

Cleaving is considered the most dramatic of all the steps in diamond cutting because the whole future of the diamond rides on that one tap of the mallet. When the stone is a large and important one, that can mean hundreds of thousands of dollars.

32. Bruting. The next cutting step is bruting, which is also called rounding or girdling. This forms the girdle, which is the basic dimension of the finished diamond.

The bruter sets the stone in a dop and fixes the dop in a lathe which spins at high speed. Using another diamond set in the end of a long bruting stick, he gradually grinds off the corners until the spinning diamond is round at its thickest part. In the process he partially rounds the diamond in the bruting stick, and this is later put on the lathe to finish its own bruting.

Diamonds finished in the round or brilliant cut go through the bruting step in this way. Those finished in the oval, marquise and pear shape cut usually go through the same step, but by a slightly different process. Emerald-cut diamonds have their girdles formed in a different way.

33. Blocking. The primary facets of the diamond are ground onto it by the blocker. He works with a cast iron plate called a scaife, impregnated with oil and diamond dust, which revolves like the turntable of a phonograph. He sets the diamond in a holder and lowers it onto the spinning plate, and he has to change its position for every facet.

The table, which is the largest facet of the diamond, is usually the surface formed when the stone is sawed or cleaved. The girdle has been formed with its plane parallel to the table. Now the blocker grinds a facet between the table and the girdle at an angle of 34.5º to the plane of the girdle. Then he grinds two more facets, one on either side exactly between the first two. These are called crown or bezel facets. Then he turns the stone over and grinds four corresponding pavilion facets below the girdle, each 41º to the girdle plane.

In the second stage of blocking, he grinds four more bezel facets above the girdle, each exactly between two of the first four facets, and four more pavilion facets to correspond. It takes a long time for each facet to be ground, and the blocker has to check the process constantly to see that not too much is being ground away on any one facet.

At this point the diamond looks like the familiar gem. It has 17 facets—8 bezel facets and the table above the girdle, and 8 pavilion facets meeting in a point below the girdle. The blocker then grinds off the point in a tiny culet facet that is exactly parallel to the table and the plane of the girdle.

For diamonds that are 50 to the carat or smaller, this can be the end of the line. Such diamonds, with only 18 facets, are called single cuts.

34. Brillianteering. This is the final cutting step for 58-facet diamonds, which are called full cuts. The brillianteerer works with the same scaife that the blocker used, and he cuts the last 40 facets.

Of these, 24 are placed in threes between the 8 bezel facets; two extend up from the girdle, and the third extends down from the table. The other 16 are placed in pairs between the pavilion facets, extending down from the girdle. As each new facet is cut, of course, it changes the shape of the adjoining facets.

Cutting is a long, exacting and expensive process. Cutters are skilled craftsmen who must use the judgment gained by long years of experience to bring out the full beauty of a diamond. Automation is beginning in the cutting industry, with smaller diamonds.

35. Shapes. The finished diamond may have any of several shapes, each of which is also called a cut. The brilliant cut, or round, is the most popular of all diamond shapes. Round diamonds can be finished, with 17 or 18 facets, in sizes so small that they will run more than 200 to the carat. This type of brilliant is known as single or eight cut.

The oval cut, as its name implies, is an elongated round. The marquise cut is rounded in the middle and pointed at each end, like a weaver’s shuttle. The pear shape is rounded at one end and pointed at the other. The heart shape is essentially a pear shape with a notch in the rounded end.

The proportion of length to width may vary within each of these ‘fancy’ cuts so that is possible, for example, to have both ‘thin’ pear shapes and ‘fat’ pear shapes. Each of these cuts has the same 58 facets as the brilliant cut, but the shapes of the facets are different. Some larger diamonds in these cuts have girdles thick enough for additional facets around them.

The emerald cut (and its companion, the square cut) also has 58 facets, all of which are very close to rectangular. There are 24 facets and the table above the girdle, and 24 facets and the culet below; the remaining 8 facets are around the girdle.

Any of these shapes may be used as the solitaire or principal diamond in an engagement ring. They may also be used in other types of jewelry. The advantage of the fancy shapes for the cutter is that they usually can be cut from irregular pieces of rough with less loss of weight than a round can be cut. Their advantage for the customer is that they tend to look larger than a round diamond of the same weight.

But these are not the only shapes of diamonds being cut today. For the most part, the others are small diamonds which are set as side stones in rings or as secondary stones in other types of jewelry. Usually they are cut in these shapes to get maximum weight out of irregular small pieces of rough.

The baguette is thin and rectangular, like an emerald cut with 17 facets. The tapered baguette is wider at one end than the other, like a tall trapezoid. The trapeze follows the standard trapezoid shape, with the long sides parallel and the short sides angled toward each other.

The triangle is a three-sided stone, as the name implies. The kite shape looks like a kite, or two triangles of different sizes. The lozenge is like the diamond pip on a playing card, or two triangles of equal sizes. The half moon has the shape of a crescent.

Selling Diamonds (continued)