Cornwall Slate vs Green Onyx
Both are Sherwin-Williams colors. Hue-wise, Cornwall Slate belongs to the grey family and Green Onyx to the green-greige family. With LRVs of 29 and 31, they'll behave almost identically in terms of how much light they reflect back into a room. They share a neutral quality — useful to know if you're layering them in the same space. At ΔE 6.9, the difference is perceptible but not dramatic — the two can work harmoniously in the same space. Below you'll find 3 real-room photo comparisons where both colors appear side by side, plus 5 simulated room previews.
Cornwall Slate vs Green Onyx in Real Spaces
3 real rooms side by side. Cornwall Slate 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
Living rooms test a color across a full range of conditions — morning sun, afternoon shade, and evening lamp light all shift how both of these read. At this scale, the choice between them becomes clear in a way that a swatch alone can't communicate.
Bathroom
Bathrooms amplify color — the enclosed space and reflective surfaces make what reads subtle elsewhere feel more present here. Side by side like this, the difference is easy to read — which is exactly why seeing them in a real space is more useful than comparing chips.
Kitchen Cabinets
On cabinetry, undertone and temperature become more pronounced against countertops and hardware. Side by side like this, the difference is easy to read — which is exactly why seeing them in a real space is more useful than comparing chips.
Color Details
Cornwall Slate vs Green Onyx Simulated Comparison
5 simulated room previews — drag the slider on each to see Cornwall Slate 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.
More Cornwall Slate comparisons
See how Cornwall Slate stacks up against other well-photographed colors across different brands and tones.
