CIEDE2000 (ΔE00) is a standard formula for how different two colors look to a human observer. A larger number means a larger visible difference.
In more detail
It works in CIELAB lightness, chroma and hue, with corrections for how the eye sees each region. Our Dichroscope calls a ΔE00 under 1 “none”.
How we measure it
The Dichroscope uses ΔE00 to class pleochroism through 5 mm in daylight. Ruby reads 17.9 and sapphire 41.6 (strong), emerald 15.3 (distinct) and amethyst 3.3 (weak). We check our formula against the 34 test pairs of Sharma, Wu and Dalal (2005).
Related terms
- Pleochroism: Pleochroism is the property of a colored doubly refractive stone to show different colors in different directions. It happens because the stone absorbs its rays differently.
- Dichroscope: A dichroscope is a gem-testing instrument that shows a stone's two pleochroic colors side by side. In the calcite type, a calcite rhomb splits the light into two images of a small window.
- CIE colorimetry: CIE colorimetry turns a light spectrum into a color by weighting it with standard human color-matching functions. Standard illuminants, such as D65 (daylight) and A (incandescent lamp, 2856 K), define the light.