Before any further processes are performed, each Rand diamond is checked against its blueprint. The next phase is to achieve the highest degree of roundness possible. This is the duty of the Rondister.

While the initial work on the diamond has been largely performed by machinery, human hands perform all subsequent phases as they can achieve higher quality for these phases than the best technical equipment.

A Rondister will mount the diamond on a mini lathe. Using another diamond mounted on a stick, he or she will carefully polish the edge of the spinning diamond to create a shape that is perfectly round and has a girdle thickness that is perfectly even around the widest part of the diamond. Only a human can perform this task to the degree of accuracy necessary to conform to a diamond's blueprint.