Slate (BM CW-700) vs Limestone (SW 9599)

Living room with walls painted Benjamin Moore Slate CW-700 (simulated) — Slate BM CW-700#A3A8A8, LRV 39.1

Living room with walls painted Sherwin-Williams Limestone SW 9599 (simulated) — Limestone SW 9599#6A655C, LRV 13

Illustrative room. Screen colors vary; test a sample before you paint.

Quick decision

Lighter: Slate, LRV 39.1 vs 13.
Warmer: Limestone (Lab b* 5.8 vs -0.6). Slate reads neutral gray; Limestone reads greige.
North rooms: Slate: keeps more brightness (L* 64.4 vs 38.9 in north light) and drifts less gray (chroma drop 0.0 vs 4.5).
Trim that works: Alabaster BM 876, #F2EFE8, LRV 85.1: the Benjamin Moore white closest in hue to both.
Closeness: deltaE 24.7, clearly different. At 24.7, treat them as different colors.

See each color

SlateBenjamin Moore, BM CW-700LRV 39.1, #A3A8A8

LimestoneSherwin-Williams, SW 9599LRV 13, #6A655C

Slate (BM CW-700) is much lighter than Limestone (SW 9599) and cooler: LRV 39.1 vs 13, deltaE 24.7 (clearly different).

Side by side

Measure	Slate	Limestone	Gap
Brand	Benjamin Moore	Sherwin-Williams
Color code	CW-700	SW 9599
Hex	#A3A8A8	#6A655C
RGB	163, 168, 168	106, 101, 92
HSL	180°, 3%, 65%	39°, 7%, 39%
LRV (light reflectance value)	39.1	13	+26.1
Lab L*	68.5	43.0	+25.5
Lab a*	-1.8	0.2	−2.0
Lab b*	-0.6	5.8	−6.4
Undertone	Neutral	Warm
Temperature	neutral	warm
Color family	Gray	Brown

Same paint, two kinds of light

Slate (BM CW-700), published as #A3A8A8

North light (cool, indirect)
#929EA6

South light (warm, direct)
#B5B2A8

Limestone (SW 9599), published as #6A655C

North light (cool, indirect)
#5B5C5A

South light (warm, direct)
#796E5C

These swatches and the rooms above are a simulation, not a measurement. How the visualizer works

Which should you pick

Rules of thumb computed from the LRV and Lab values in the table above; no room test was done.

Pick Slate (BM CW-700) for a small room or a north-facing room, because it is 26.1 LRV points lighter (39.1 vs 13), so it bounces back more of the limited light
Pick Slate (BM CW-700) for a south-facing room, because its Lab b* is -0.6 against 5.8, so it is the cooler of the two and offsets warm direct sun
Pick Limestone (SW 9599) to warm a north-facing room, because it is the warmer of the two (Lab b* 5.8), which counters cool indirect light

Closest matches to Slate in other brands

Closest matches to Limestone in other brands

Common questions

Is Slate the same color as Limestone?: They are clearly different: a CIEDE2000 difference of 24.7. Slate and Limestone are different colors.
Which is lighter, Slate or Limestone?: Slate, with an LRV of 39.1 against 13.

Full pages

By Paint Pairs. Color data from manufacturer specifications, via PaintDB. The most-viewed colors are checked against each manufacturer's own color page.

Published 2026-10-01. Updated 2026-10-01.

Sources: LRV and hex as published by the manufacturer, via PaintDB (CC BY 4.0). Color differences are CIEDE2000 values computed by this site from the hex values (data snapshot 2026-10-01). Color names and codes belong to their manufacturers.