évention

CONT: La taille nécessite d'encimenter la pierre au bout d'un bâton dont l'inclinaison sur la meule est maintenue constante par appui sur un évent (sorte de cône renversé comportant une série d'encoches, fixé verticalement à côté de la meule).
OBS: Équipement utilisé pour la taille des pierres de couleur. Pour la taille des diamants, on utilise la pince (tang).

CONT: ... you can see the basic set up of a traditional jamb peg faceter. The spinning lap provides the grinding and polishing surface, the wooden ""dop"" sticks to which the rough is adhered, serve to hold the stone in position as various cuts are made. The angle of the cut is controlled by placing the dop stick in a particular hole, the depth of cut is controlled by the amount of time the piece spends in contact with the lap and how hard the facetor presses down on it, and the radial position is controlled by removing, slightly rotating, and reinserting the dop stick in its hole as each different cut is made. Most stones that are cut on such equipment are referred to as ""native cut.""
CONT: Although modern highly engineered faceting machines have replaced jamb pegs in much of the world, these older systems are still widely used, and a substantial proportion of the gems in commerce today have been cut by them.