Shade Matching Calculator

It uses CIE76 -- the straight Euclidean distance between the sample and target points in L*a*b* space (square root of the sum of squared L*, a*, and b* differences). This is the original, simpler Delta E formula; it is not the same as the newer CIEDE2000 formula, which weights the three color dimensions unevenly and generally correlates better with how people actually perceive color differences.

They function as a widely used rule of thumb rather than a single official standard. A separately published dental color-difference study (Paravina et al., 2015) reports 1.2 and 2.7 as its 50:50% perceptibility and acceptability thresholds for CIELAB Delta E, which is close to but not identical to this calculator's 1.0/3.5 cutoffs, so treat either set as a guideline rather than a hard pass/fail rule.

Value Assessment is based on ΔL* (Sample L* minus Target L*), which is negative when the sample reads darker than the target and positive when it reads lighter. As Sample L* rises past the Target L* value, ΔL* crosses zero and the assessment flips direction, which is exactly the behavior a lightness-difference indicator should show.

Yes -- Chroma Assessment compares the combined a*/b* magnitude of the sample against the target independently of the overall Delta E figure, so a restoration can land close enough overall to pass a Delta E cutoff while still reading noticeably over- or under-saturated on the chroma comparison specifically.

If one uses CIE76 and the other uses CIEDE2000, the two formulas can produce meaningfully different numbers from identical L*a*b* inputs -- published research shows gaps of roughly 30-50% at typical dental color differences. Always confirm which formula a given tool or paper is using before comparing Delta E values across sources.