Current Edition Checked October 24, 2026
Color acceptance by instrument depends on agreeing the formula, illuminant, observer, and tolerance in writing.
What It Covers
How color is measured by spectrophotometer and expressed as L*, a* and b* coordinates, and how differences are calculated as ΔE.
Who It Applies To
Anyone approving color by instrument: mills, dye houses, garment and product makers, and their buyers.
Key Requirements
- A physical or digital standard agreed for each color, with its illuminant and observer.
- A color difference formula (CIEDE2000 or CMC) and a tolerance, stated in the specification.
- Instrument calibration and sample preparation controlled, so readings are comparable.
- Metamerism checked under a second illuminant.
What an Auditor Asks to See
- The color standard, the formula, and the tolerance for a product.
- Calibration records for the spectrophotometer.
Where Systems Fall Short
- Approvals made against last season’s sample instead of the standard.
- ΔE tolerances quoted without the formula, which makes them meaningless.
How QES Helps
Color approval procedures that end the arguments, because the numbers are agreed before the dyeing starts.
Related Standards
Sources. CIE — International Commission on Illumination, colorimetry standards (opens in a new tab). Status checked October 24, 2026. This page summarizes CIE L*a*b*; it does not reproduce or replace it. Buy the standard from its publisher, or read the regulation in its official text, before relying on a detail. Not legal advice.