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Color and Light · entry 35 of 52
Turquoise sits between blue and green on the spectrum and is named after a gemstone.
The longer version
The hue occupies the boundary between green and blue, sitting near the middle of the short-to-middle wavelengths. Because the two neighbouring categories overlap there, people disagree about whether a given sample counts as greenish blue or bluish green. Both cone signals fire at comparable strength, which is what makes the category uncertain.
The name comes from a mineral, a hydrated copper aluminium phosphate, whose colour ranges from sky blue to apple green depending on trace impurities. The word entered English from French, originally meaning Turkish, because the stone reached Europe through Turkey. Similar boundary hues include teal, cyan, and aqua.
Where this entry sits
These facts explore how light behaves and how human eyes turn it into the colors we see. Along the way you meet rainbows, prisms, mirrors, shadows, lasers, and optical tricks that fool our vision every day. The full list sits on the Color and Light page, where every entry is listed in order.
More From Color and Light
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Read 37The color of a flame changes with temperature, shifting from red toward blue as it gets hotter.
Read 38Optical illusions trick the brain by exploiting the shortcuts it uses to interpret light and edges.
Read 39Afterimages appear when staring at a bright color fatigues the cone cells responding to that hue.
Read 40A gray square looks lighter on a black background than the same square on a white one.
Read 41Neon colors seem to glow because they reflect more light than ordinary dyes can.
Read 42Fluorescent materials absorb invisible ultraviolet light and re-emit it as visible color.
Read 43Glow-in-the-dark objects store light energy and release it slowly over several minutes.
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