Coastal Plain vs Green Onyx
Coastal Plain and Green Onyx come from the same Sherwin-Williams collection. Coastal Plain reads as green-grey, while Green Onyx reads as green-greige — two distinct hue families, not close cousins. The 5-point LRV gap — 37 for Coastal Plain vs 31 for Green Onyx — means Coastal Plain will open up a space more effectively. Both share a neutral character, which means they'll respond to light and surrounding materials in similar ways. ΔE 5.8 means they're clearly different, but not dramatically so — they'd pair well in the same room. Below you'll find 3 real-room photo comparisons where both colors appear side by side, plus 5 simulated room previews.
Coastal Plain vs Green Onyx in Real Spaces
3 real rooms side by side. Coastal Plain and Green Onyx are close enough that the difference can be hard to judge from a chip alone — these photos show how each reads at scale, across different spaces and lighting conditions.
Living Room
A living room wall sees more varied light than almost any other surface in the house, which makes the choice between these two more nuanced than a chip suggests. Coastal Plain reads slightly lighter here — a subtle but real difference in how open the space feels.
Bathroom
Small bathrooms intensify color. A shade that seems quiet in a larger room can feel immersive when you're surrounded by it on four walls. Coastal Plain has the edge in reflectance, which shows as a quiet sense of added space rather than an obvious contrast.
Kitchen Cabinets
Cabinet color is always seen in context — against countertops, backsplash, and hardware — which amplifies undertone differences that might disappear on a plain wall. Coastal Plain has the edge in reflectance, which shows as a quiet sense of added space rather than an obvious contrast.
Color Details
Coastal Plain vs Green Onyx Simulated Comparison
5 simulated room previews — drag the slider on each to see Coastal Plain on one side and Green Onyx 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.