In this study, I investigate how Roman patrons' use of gemstones in domestic decoration encouraged guests to forgo their traditional role of observer and to instead actively engage with the ornamentation in elite residences. I specifically analyze the gemstones depicted in the Second-Style wall-paintings in Triclinium 14 in the Villa A at Oplontis and Cubiculum M in the Villa of P. Fannius Synistor at Boscoreale (50-40 BCE), as well as the two mirror-like obsidian slabs embedded into the east peristyle wall of the House of the Golden Cupids in Pompeii (mid-1st century CE).

Though the conversation is nascent, accepted interpretations regard ornamental gemstones as mere markers of Rome's expansive military conquests and of Hellenization. However, I seek to transcend gemstones' symbolization and argue that, in select homes, ornamental gemstones fostered an immersive environment that directly inserted guests into the decorative programs of their houses to entertain and impress the patron's guests. 

Focusing on materiality and spatial relationships, I extend beyond the conventional considerations of architecture, history, and chronology to determine gemstones' active role in shaping the functions and activities of these lived spaces for over a century. I also adopt ancient literary interpretations of gemstones as paradoxical objects that embody nature and art simultaneously, thus blurring the boundary between natural and man-made. I suggest the inherent duality of gemstones then resonates with the slippage between the real and engineered experiences offered in elite Roman residences, and that this shared ambiguity is precisely where houses ornamented with gemstones derived their immersive capabilities.

Through the masterful manipulation of light and shadow, the incorporation of Egyptian blue, and the deliberate semblance to the tangible gemstones guests encountered throughout the Roman world, the painted gemstones in Triclinium 14 and Cubiculum M captivated more than just guests' sense of sight. I propose that the resulting multisensory experience transformed the rooms' flat painted walls into gateways that opened to a convincingly real three-dimensional world of art that guests felt as though they could enter or touch while dining in these rooms.

I suggest the obsidian mirrors, instead, immersed guests into the House of the Golden Cupids' decorative program by momentarily allowing guests to become the art itself. Embedded into spaces typically occupied by painted vignettes, the obsidian mirrors effectively replaced the peristyle's painted motifs with dynamic reflections of the living guests. Additionally, the highly-polished black peristyle walls, akin to obsidian, enlivened the painted vignettes, causing them to appear just as animated as the obsidian reflections, and therefore encouraging guests to see themselves among the art dancing across the peristyle walls. I also posit that the reflectivity of the obsidian slabs invited guests' participation in the house's decorative program by calling guests to find material connections, specifically with the theme of light and reflection, and thus allowed guests to become participants in the residence's multifaceted materiality.

Ultimately, this study uses Roman patrons' imaginative employment of decorative gemstones as a medium for deciphering the understudied but integral relationship between ornamentation, materiality, and the social politics of lived spaces.