Grey is quietly fascinating and often overlooked. Grey glass originates from the early 1900s to the 1920s, and the darker the grey, the earlier the piece. That makes it an excellent dating marker: a dark, heavy grey fragment is almost certainly Edwardian or earlier.
Grey is classified as ultra-rare on most rarity scales, rarer than cobalt blue, roughly equivalent in scarcity to orange. It’s not associated with any single UK beach but tends to show up where older industrial glass is present. North East England beaches, particularly around Seaham and the Northumberland coast, are the most likely hunting grounds for grey given the concentration of Victorian industrial glass in that region.
Blast Beach (Seaham) is worth mentioning specifically. Blast Beach is noted for its black glass, and very dark grey is often confused with black until held to the light.
Best Place to find grey glass