Diamond Cutting and Polishing
Learn all about the historic skill of diamond cutting and polishing and how it impacts the iconic diamond sparkle
Diamond Cutting is a skilful art done by craftsmen called lapidaries, mainly done in Antwerp diamond district in Belgium, Surat, Gujarat state in India. The other important diamond centres are Tel Aviv and New York city.
The ‘Cut’ refers to two meaning – The shape of the diamond, round, oval, pear etc. The second relates to the specific quality of cut within the shape – brilliance, radiance, miners, rose etc. The quality of the cut effects the price greatly.
The main priority of the lapidaries is to optimise this rough diamond; choosing the most effective cut for the rough diamond. His main aim is to preserve as much carat weight as possible and avoiding capturing an inclusion, as well as cutting a shape which is in high demand within the market place to make the perfect engagement ring
Diamond Cutting Process
The history of diamond cutting and polishing has its origins in India, where it was discovered a long time ago by Indian lapidaries that a diamond could be made to sparkle simply by grinding another diamond against it.
The rough diamond is divided into two parts by sawing or cleaving. Most stones are sawn across the ‘grain’ (visible evidence of the diamond’s crystal structure) by a paper-thin metal disc coated with diamond dust revolving at high speed or by laser. The stones that are marked for cleaving are split along the grain by a single blow from a steel blade.
After cleaving or sawing, the corners of the diamond are rounded off by a process known as bruting or girdling (only round brilliant cuts require this step). The stone is cemented into a ‘lathe’, a holder that fits on a turning shaft. Another diamond is cemented to the end of a long rod held under the bruter’s arm. As the lathe rotates, the two diamonds are brought together and grinded to shape. Diamond dust is produced from this process and is used in further sawing and faceting.
The brilliant now has a girdle-a sort of rim at the widest part by which it is usually set. The size or position of the girdle should not change throughout the rest of the diamond cutting process.