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Diamond processing

To the non-professional, an unpolished rough diamond appears to be very much like a dull piece of glass. Only when it is polished and facetted, it ascends to its full glory, displaying the sparkling brightness and splash of colours for which it is famous. From the time the diamond is transformed from a rough stone into a gem set in an item of jewellery, it has lost half of its weight. Before the cutting and polishing process begins, a thorough examination of the rough diamond is conducted. We can distinguish 4 different phases in diamond processing: drawing/marking, cleaving/sawing, bruiting and polishing.

 

Drawing/marking

A diamond is marked in order to determine how it may be cut to the greatest advantage. Traditionally, an experienced diamond expert used an Indian ink pen to do this. More recent methods involve computer-aided design systems that analyze the stone, and then mark their surface using a very precise laser beam.

 

Cleaving/sawing

Cleaving is a method of splitting a diamond parallel to the direction of crystal grain with a single blow. It is done to divide the stone into two or more pieces, or in order to remove impurities or irregularities. Sawing is a method of splitting a diamond against the grain of the crystal.

 

Bruting

Bruting involves the shaping of the base of a diamond, by which it more or less receives its form as a polished diamond. The circumference of the cut stone forms the shape of the girdle, which is the narrow band that encompasses the edge of the plane separating the crown and the pavilion of a polished gemstone. Bruting can be done manually but most is done mechanically today. More modern cutting methods involve laser beams.

 

Polishing

Polishing is the process which facets the diamond. The most popular polished diamond is a round brilliant, which has a total of 57 facets – the upper place, or table facet; the crown or section above the girdle, which includes 32 facets; and pavilion, or section below the girdle, which includes, 24 facets.