Heavy Libra 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.

Latin libra, scales-of-the-zodiac. As a color modifier, libra implies a scales-and-air-sign-and-Venus-ruled-cardinal-air quality, the visual register of Roman-Libra-and-scales-of-justice hand-scales-and-air-sign-and-Venus-ruled-cardinal-air Roman-Libra-and-scales-of-justice-and-Themis-Astraea libra-and-scales-and-air-sign surfaces under Roman-Libra-and-scales-of-justice-and-Themis-Astraea autumn-equinox-and-September-and-October cardinal-air-sign-light. Sits at the modifier-and-zodiac end of the grid, parallel to virgo and scorpio 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.