Trustworthy Gleam Sky

Old English trēow, trust — adjectival suffix -worthy. As a color modifier, trustworthy implies a clear-and-reliable-and-honest quality where the hue carries the visual register of confidence-deserving-and-faithful-performance design-element. Sits at the crisp-and-honest end of the grid, parallel to reliable and dependable in usage.

Old English glǣm, brightness-or-shine. As a color modifier, gleam implies a low-and-glancing-and-bright quality, the visual register of polished-armor-and-river-water-gleam hand-polished-and-glancing-and-bright polished-armor-and-river-water-and-blade-edge gleamed-and-polished-and-glancing surfaces under polished-armor-and-river-water blade-edge-and-helm-and-shield medieval-tournament-light. Sits at the modifier-and-mood end of the grid, parallel to glint and sheen in usage.

The blue of a clear sky at noon — produced by Rayleigh scattering, the preferential dispersion of shorter wavelengths through atmospheric molecules. Air itself is colorless; the color we see is sunlight scattered toward our eyes by every cubic kilometer above. The reference shade is mid-latitude noon under a high pressure system: a clean, slightly green-shifted blue with the luminous depth of light scattered across an entire hemisphere of air.