Certain Cape Indigo

Latin certus, fixed / sure — sharing root with English concern and certify. As a color modifier, certain implies a saturated-and-unambiguous quality where the hue declares its character without hesitation. Sits at the bold-and-confident end of the grid, parallel to assured and decisive in usage.

Latin cappa, hooded-cloak. As a color modifier, cape implies a hooded-cloak-and-shoulder-cape quality, the visual register of Spanish-capa-and-Italian-cappa-magna hand-hooded-cloak-and-shoulder-cape Spanish-capa-and-Italian-cappa-magna-and-Portuguese-capa cape-and-hooded-cloak-and-shoulder-cape surfaces under Spanish-capa-and-Italian-cappa-magna-and-Portuguese-capa Iberian-and-Italian-Renaissance Iberian-cape-light. Sits at the modifier-and-textile end of the grid, parallel to cloak and cope 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.