Standard CRI (Ra) is misleading as a standalone metric. Ra measures only R1 through R8 — eight pastel test colors. The critical R9 value, which measures saturated red rendering, is excluded from the Ra calculation yet affects skin tones, wood, and food appearance.
R9 Requirements
A fixture labeled "CRI 90" with R9 below 20 will render skin tones grey and wood tones flat. Industry standards specify R9 ≥ 50 for genuine CRI 90 classification and R9 ≥ 90 for CRI 95+. Always request the full test report showing individual R1-R15 values, not just the aggregate Ra number.
Retail Impact
In a jewelry store case study, switching from fixtures with R9=25 to R9=85 resulted in a 12% increase in average transaction value according to the store owner. The color of gold, gemstones, and precious metals changes visibly under different R9 levels.
Cost Justification
The CRI 80 to CRI 90 premium is approximately 15-25% in fixture cost. Over a 50,000-hour rated life at $0.12/kWh commercial electricity rates, this translates to roughly $0.018 per operating hour. For retail environments where lighting quality directly affects purchase decisions, this cost is below the credit card processing fee on a single transaction.
Alternative Metric
Request the TM-30-18 test report instead of or in addition to CRI Ra. TM-30 provides two metrics: Rf (fidelity, similar to CRI) and Rg (gamut, indicating color saturation). These two numbers together provide a complete color rendering assessment. Per IES TM-30-18 and CIE S 025 standards.
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