Vantablack
Vantablack is a class of super-black coatings with total hemispherical reflectances (THR) below 1% in the visible spectrum. The name is a compound of the acronym VANTA and black.
Olo (color)
Olo is an imaginary color that can only be seen using specialized tools that exclusively activate the M cone cells on the retina, without activating the L and S cone cells at the same time.
Where to Find the Colors Your Screen Can’t Show You
An atlas of the vibrance of the real world

The great German polymath Johann Wolfgang von Goethe was born #onthisday in 1749. As well as penning novels, poetry, criticism, and dramas, he also wrote various scientific treatises, including his 1810 book Zur Farbenlehre (Theory of Colours): publicdomainreview.org/essay/black-on-black #OTD