Just fyi -- I'm not a potter but I have a set of dishes (plates, bowls, cups, saucers, and various serving pieces) that have an identical looking glaze as the Helen Levi set pictured at the top by the OP -- that bright, matte blue. I got them at a ceramics market in a town outside of Mexico City in 1989. I had some breakage tested when I got back to the US and was told they were not toxic, though the three or four times I did use them, I noticed that anything acidic (lemon juice or tomatoes) would spot (lighten? etch?) the finish. I put them away and have always meant to get them retested –– I'm not sure if staining necessarily means leaching. Until this post I've never seen any others like them.
Does anyone know of a reliable lab in the Seattle area where I could get them tested?
