Heavy Prism Tanzanite

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.

Greek πρῖσμα, something-sawn. As a color modifier, prism implies a Newtonian-rainbow-and-spectrum-splitting quality, the visual register of Newton-Optics-and-Cambridge-prism hand-Newtonian-rainbow-and-spectrum-splitting Newton-Optics-and-Cambridge-and-Trinity-College-prism prism-and-Newtonian-rainbow-and-spectrum-splitting surfaces under Newton-Optics-and-Cambridge-and-Trinity-College-prism 17th-century-natural-philosophy-and-rainbow-experiment spectrum-light. Sits at the modifier-and-cosmic end of the grid, parallel to corona and plasma in usage.

A blue-violet variety of zoisite — discovered in 1967 in a single small area of northern Tanzania near Mount Kilimanjaro and marketed by Tiffany & Co. shortly after. The color refers to a faceted tanzanite cut to maximize its strong pleochroism: a saturated, slightly violet-shifted deep blue-purple with the gem's signature internal life. Cooler than amethyst, warmer than iolite, with the gem-trade specificity of a stone that occurs in exactly one place on Earth.