RAL 820-4 vs Blue Grotto
Where RAL 820-4 belongs to RAL Effect's range, Blue Grotto is a Sherwin-Williams color. Hue-wise, RAL 820-4 belongs to the blue-grey family and Blue Grotto to the blue family. Blue Grotto (LRV NaN) reflects noticeably more light than RAL 820-4 (LRV 23), a difference of NaN points that becomes especially apparent in rooms with limited natural light. With a ΔE of NaN, the contrast is hard to miss. These aren't variations on a theme — they're two different answers to the same question. Below, 5 simulated room previews show how each color reads at scale — real-room photos will be added as they become available.
Color Details
RAL 820-4 vs Blue Grotto Simulated Comparison
5 simulated room previews — drag the slider on each to see RAL 820-4 on one side and Blue Grotto on the other.
Digital color is approximate. These simulations are generated from the manufacturer's hex values and overlaid on grayscale room photos — your screen's calibration, brightness, and viewing angle all affect how they render. Before committing to either color, test physical samples in your own space under the light you actually live with.
More RAL 820-4 comparisons
See how RAL 820-4 stacks up against other well-photographed colors across different brands and tones.
