Girdle Thickness

The girdle is the edge of the diamond and this is measured in relative thickness and the type of finish.

Girdles always used to be bruted which meant two diamonds were ground round on each other. This resulted in a dull waxy appearance. These days most larger diamonds are faceted with lots of very small flat facets or they are polished smooth. A faceted girdle does not improve a diamonds grade, although a bruted girdle looks much worse if the stone is a 'fish-eye'.

Girdle thickness should ideally be between thin, medium and slightly thick. There is almost always some variation in girdle thickness around a stone. There are often four small, thin areas reflecting the original shape of the octahedral rough diamond crystal. These thin areas should not be set in a claw setting in an exposed position because they are also cleavage directions. If a diamond is struck in these directions on extremely thin to thin girdles they can and will chip.

Diamonds with thick, very thick, or extremely thick girdles weigh considerably more but may be much better buys. There will be small amounts of light loss when viewed in some directions.

Diamonds with very thin girdles are not recommended for claw set ring settings but are OK in pendants and earrings. There is always the risk of a girdle chipping during setting if it is too thin.