Some extra facets will be very obvious, as in this case, where others will be very slight.

A modern round brilliant has 58 facets, (57 with a pointed culet), which means that adding an additional one would be considered an extra facet. In order to save weight, a cutter might leave intact an exceptionally large natural that extends into the crown or pavilion and simply polish it, leaving an obtrusive extra facet. In other cases, an extra facet will be left intact, due to an absence of cutting quality, or perhaps a girdle that is so extremely thin as to leave no room to further diminish it. Regardless of cause, it does not belong. Usually an extra facet will not affect clarity unless it is very obvious, or it distinguishes between a Flawless and an Internally Flawless diamond. Occasionally a cutter will intentionally place additional facets on a stone to achieve a specific design that follows an obvious symmetry. These are not considered extra facets.