Gilbert Stuart is low-key throughout, a quality associated with Nocturnal Sienna - deep shadows dominate the composition. Gilbert Stuart orchestrates warmth above all else - reds, ambers, and siennas take the lead. Chroma is kept low across all colours, producing the soft, enveloping quality that characterises tonal painting. Gilbert Stuart gives 26.7% of the composition to a single #15110F - a decisive chromatic anchor. The saturated accent, #673A26, registers at 4.7% - sparse enough to feel like a deliberate surprise. At 62 units of value range, the palette has the tonal breadth to sustain complex spatial readings. The combination of low values, muted chroma, and compressed range is the signature of the Tonalist mode - painting as atmosphere. Palette 9 sits within the larger chromatic argument that Gilbert Stuart's complete body of work advances.