Heavy Past Indigo

Old English hefig, weighty — cognate with heave. Used as a color modifier since at least the seventeenth century to indicate weight in saturation as much as value: heavy with pigment, heavy-bodied. In the engine's adjective grid, heavy sits alongside deep and plush in the dark-and-saturated quadrant. Closer to a fabric description than a pure value word.

Old English passed, gone-by. As a color modifier, past implies a memory-and-faded-time quality, the visual register of vintage-and-period multi-decade faded-and-storied memory-laden period-correct-faded surfaces under multi-decade faded-and-storied period light. Sits at the modifier-and-time end of the grid, parallel to yore and eld in usage.

Indigofera tinctoria, the South Asian legume whose leaves yield the deep blue dye that has clothed humanity for at least four thousand years — Egyptian linen, Mayan textile, the slave-grown plantations of Carolina. The color refers to a freshly indigo-dyed cotton thread: a saturated, slightly violet-shifted deep blue with the slight lustre of a fiber surface oxidized in air. Deeper than cobalt, cooler than royal.