How are diamonds shaped?
Diamond is one of the hardest materials known to man, so naturally this leads many people to
wonder - how do jewellers cut them into such dazzling shapes? The answer, generally speaking, is that
they use other diamonds. Diamond cutting and shaping is an incredibly specialised process involving
many steps: the many-faceted gems you see adorning rings and necklaces don't get that way overnight!
Before any cutting or shaping is done, manufacturers will assess the potential of a rough diamond -
that is, a freshly-mined diamond in its natural state. In the past this would be done by eye alone, but
modern techniques include using a scanner to create a 3D computer model of the rough diamond, from which the
manufacturer can decide how best to cut and shape it.
The next step is cleaving or sawing. The rough diamond is placed in a cement or wax mould to hold it
in place, before a sharp groove is cut into the tetrahedral plane (the weakest point). A sharp hit with a hammer
'cleaves' the diamond into smaller pieces: as diamonds are both incredibly hard and very brittle, they tend to
split quite cleanly.
Alternatively, the diamond may be cut with a diamond saw or a laser, a process which takes hours.
During sawing, the cutter will decide which parts of the diamond will become the table (the flatter
'face' of the gem) and the girdle (the outer edge with the largest diameter). Once the diamond is of
the desired size, the facets of the stone are ground flat against another diamond - this can be done
by hand (bruiting) or by machine (cutting).
Once the intricate work of cutting the facets is complete, the diamond is polished on a wheel called
a scaif. The scaif is lubricated with an abrasive paste of olive oil and diamond dust that smooths out any
remaining rough parts on the diamond. When this has been done to the cutter's satisfaction, the diamond is
boiled in a solvent of hydrochloric and sulphuric acids to remove any dust and oil. The gemstone is now complete -
ready to be mounted on a ring, necklace or any other piece of jewellery!