CRI (Ra) was developed in 1965 for fluorescent and incandescent lamps. It tests 8 pastel colours, none very saturated. LEDs with red gaps can score Ra 90 but render saturated reds terribly. NIST's CQS (Color Quality Scale, 2010) tests 15 saturated VS samples. IES TM-30 (2015) adds Rf (fidelity) + Rg (gamut). EP12 introduced CRI/TLCI/TM-30; this episode goes deep on CQS specifically.
Four ideas to carry into the next specification conversation you have.
All desaturated. Red R9 not in Ra average. Lamps with red gaps can fake high Ra. Standard since 1965, due an update.
Specifically designed for LED quality. Saturated reds, greens, blues. Plus chroma boost and CCT considerations. NIST 2010.
Rf = fidelity (how true). Rg = gamut (how saturated). Both must be reported. IES standard 2015, updated 2018.
Ra ≥ 90 + Rf ≥ 80 + Rg 90-110 + R9 ≥ 50. Belt + braces. Real fixture quality.
When CRI is enough, when you need CQS or TM-30.
| Metric | Samples / Range | Best for |
|---|---|---|
| CRI Ra | 8 pastel, 0-100 | Office, general |
| CRI R9 | Saturated red, -100 to 100 | Skin / textile |
| CQS Qa | 15 saturated VS, 0-100 | LED quality |
| TM-30 Rf | 99 CES samples, 0-100 | Modern spec |
| TM-30 Rg | Gamut area, 70-130 | Saturation |
| TLCI | TV broadcast, 0-100 | Camera |
Five scenarios where Ra 90 isn't enough.
Blue chip + phosphor LED can score Ra 90 but R9 of −20. Reds in art, food, skin look grey. Ra alone hides the gap.
Steakhouse meat needs R9 ≥ 90. Bakery breads need full warm spectrum. Hotel skin tones, guest selfies depend on it.
Cyanosis (blue), jaundice (yellow), rash (red) all depend on accurate saturated rendering. EN 12464-1 healthcare annex now demands R9 ≥ 50.
Cosmetics, jewellery, fashion. Customers see in saturated colour. Low-Rg lamps mute the products. Premium retail now demands Rg ≥ 95.
Conservation lighting must render paintings faithfully. Rf ≥ 90, narrow CCT tolerance, R9 ≥ 90.
Every premium NLC fixture's datasheet includes CRI Ra, R9 individually, TM-30 Rf and Rg, and SPD curve. Full disclosure, no hidden gaps.
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