Sharma, Wu & Dalal (2005) locate the CIEDE2000 blue-region rotation term's impact near a hue angle of 275°

Sharma, Wu & Dalal, "The CIEDE2000 Color-Difference Formula: Implementation Notes, Supplementary Test Data, and Mathematical Observations" (Color Research & Application 30(1):21-30, 2005), discuss the rotation term's (R_T) practical footprint directly: "Its impact is localized in the blue hue region (around 275°), outside of which Δθ and therefore the R_T term is rather small." The paper — the CIEDE2000 formula's own implementation-notes reference, hosted on a corresponding author's university page — reads this figure off the formula's own defining equation rather than measuring it independently: 275° is the centre constant of the hue-rotation function Δθ = 30·exp{−[(h̄′−275°)/25]²} (the paper's Eq. 16; CIE 15:2004's Eq. 8.44), and the paper notes its localization observation "is in agreement with the functional form for Δθ in Eq. (16)."

This gives claim-cielab-lacks-perceptual-uniformity-in-blue-hues and claim-cie-15-2004-blue-region-nonuniformity-motivates-ciede2000-rotation a second Tier-1 pointer carrying the specific numeric hue angle that CIE 15:2004's qualitative "the blue region" description did not — but it is not an independent second measurement. The 275° here and the rotation function in CIE 15:2004 §8.3.1 are the same formula constant, fixed when CIE TC 1-47 fitted CIEDE2000 to experimental colour-difference data (Luo, Cui & Rigg 2001; CIE 142-2001); a different author group restating the formula's own Eq. (16) is one authorship chain, not two. What the paper does add: peer-reviewed, non-CIE confirmation that the blue-region correction's practical footprint sits where the formula's constant says it does, and a Tier-1 home for the ~275° figure that an earlier Tier-4 Wikipedia mention ("hue angles in the neighborhood of 275°") floated without sourcing this strong.

The authors are explicit that this paper does not evaluate whether the correction is perceptually correct, only how it behaves mathematically — a scope limit worth carrying forward if this cluster grows toward evaluating CIEDE2000's own adequacy.