Cold-cut glass became the most prominent artistic form of decoration in the early Islamic period, especially in the ninth and tenth centuries. While this lapidary technique is as old as glassmaking itself, dating well before glassblowing was invented, Roman and Sasanian cut glass (from eastern Mediterranean and Iranian areas, respectively) provided immediate models. From Egypt to Iran, Islamic cut and engraved decoration took various forms, ranging from complex relief patterns created using mechanically operated wheels and drills to hair-width incisions made with a pointed tool.
Glass objects can be divided into six broad categories according to technique and/or decorative pattern: scratch-engraved, faceted, with disks, with raised outlines, with slant-cut decoration, or with linear decoration.
In the scratch-engraved technique, fine incisions were made using a pointed tool mounted with diamond, topaz, or corundum chips to create linear, vegetal, and geometric patterns. Facet-cut decoration, influenced by the Sasanian tradition, usually created “honeycomb” patterns of shallow facets. Raised or countersunk disks with a raised boss in the center are commonly referred to as “omphalos” (Greek for “navel”). In relief-cut glass, the background and most of the inner areas of the main design were removed by cutting and grinding, leaving the outlines and some details in relief. This group also includes Roman-inspired cameo glass—colorless glass encased by a colored layer in order to create a dramatic bichromatic contrast. In objects with incised lines, the wheel’s angle of approach to the surface, either perpendicular or at a slight angle, created the distinction between the linear and the slant-cut styles.