R9 is one of the 14 extended CRI test colors, specifically measuring how accurately a light source renders saturated red. Unlike the general CRI (Ra), which averages 8 pastel colors and can hide poor red rendering, R9 directly reveals whether reds look vibrant or dull. Many LEDs with CRI 80 have a negative or very low R9 value, causing red objects, meat, skin tones and red clothing to appear brownish or lifeless. For retail, healthcare, photography and food lighting, specify R9 ≥50 (ideally ≥90) alongside CRI ≥90. Premium LED chips like Lumileds Luxeon, Cree XP-G3 and Nichia 757 series offer excellent R9 performance. Always request R9 data from your supplier.