A gold men's signet ring with a hematite intaglio depicting the head of a Roman soldier or centurion. Product details: Stone: Hematite is a black or steel-gray mineral with a metallic luster. It is often used for carving in such rings. Technique: Intaglio (negative relief). The design is carved into the stone, creating a recessed silhouette. Subject: The profile of a warrior in a classic helmet (centurion) is a traditional and very popular motif for vintage men's signet rings, which gained particular popularity in the 20th century (for example, in the 1970s and 1980s).