What does the term "intaglio" refer to in gemstone processing?

The term "intaglio" specifically refers to a technique where designs or images are engraved into the surface of a gemstone, creating a recessed effect. This method is often utilized in the creation of seals or signet rings, where the engraved image is intended to leave an impression when pressed into a softer material. The intaglio technique allows for intricate designs to be featured visibly when the gemstone is viewed from the side or when it is used to make an impression.

In contrast, styles of cutting gems might involve different techniques or shapes but do not specifically denote the engraving process that intaglio represents. Similarly, polishing gemstones pertains to enhancing the surface finish of a gemstone rather than engraving. Lastly, gemstone inclusions refer to internal features within a stone, which are unrelated to the surface engraving process inherent to intaglio. Thus, identifying intaglio as a design engraved into the surface captures the essence of the term accurately.