The step cut is so commonly used for emerald that this style is usually referred to as the emerald cut; this is particularly true if the stone is rectangular in shape with eight sides and three tiers of facets on top and three tiers on the bottom. A square stone of the same description is referred to as a square emerald cut. Heavily flawed stones are usually cut in cabochon or carved. Small stones are frequently cut into baguettes or calibre. The round brilliant cut is rarely used, since it does not show the color of an emerald to best advantage.
Aquamarine and the other beryls are not particularly sensitive to the heat generated by any phase of the fashioning process; emeralds, however, particularly heavily flawed stones, must be treated with care, since the flaws and fractures may develop further or the stone may break.
Cabochon material may be ground in the usual manner, using carborundum wheels and regular sanders for the preliminary operations. polishing is accomplished either on leather laps with Linde A polishing powder or on felt laps with cerium oxide. If the hollow tubes in cat's-eye material tend to pick up the abrasive or polishing agent, they may be sealed off by first dipping the stone in liquid shellac and then removing it with alcohol after the stone is finished.
Transparent material is ground on diamond impregnated laps. Polishing is accomplished on tin laps with Linde A powder. An alternative method is to use a Lucite lap with either cerium oxide or tin oxide as the polishing agent. Since emeralds are usually cut to exhibit the most attractive color, carful attention must be given to orientation of the attractive color. Suggested angles are 42° for the crown and 43° for the pavilion.
