The story
From Chinese + blue. From being an artificial blue pigment invented by the ancient Chinese.
Etymology from Wiktionary, CC BY-SA 4.0.
Chinese blue
Today it means: A artificial blue pigment made from barium copper tetrasilicate (“BaO·CuO·(SiO₂)₄”), used in ancient China from the Western Zhou period (1045 BCE) until the end of the Han dynasty (circa 220 CE). Full definition →