TM-30-20, published by the Illuminating Engineering Society (IES), is a modern color quality metric that evaluates light sources using 99 color evaluation samples (CES), compared to only 8 pastel samples used by the traditional CRI (Ra) scale. It reports two values: Rf (color fidelity, 0-100) and Rg (color gamut, indicating saturation relative to reference). TM-30 provides a more accurate picture of how a light source renders real-world objects, including saturated reds and skin tones, which CRI often misrepresents. Many premium LED manufacturers now publish TM-30 data alongside CRI. For critical color applications, specify both CRI Ra ≥90 and TM-30 Rf ≥90 with Rg between 95-105 for natural, balanced color.