1751 D. Jeffries (ed. 2) Gloss. In Brilliants, there are two sorts, skew or skill facets and star facets.
1850 C. Holtzapffel III. 1330 These triangular facets are called skill facets, from the difficulty of placing them correctly.
1850 C. Holtzapffel III. 1336 A row of double skill facets are then arranged around the girdle.