Did you put another colour on top at the top to get that darker banding, or is that a natural effect of the glaze? I;ve don;e dimilar with abit of white over a darker glaze, but the colour above the band is usualy a lot different. That band and the speckling below it are what make we like this piece so much.
The glaze is called Moss Green, and it is a standard glaze whose recipe was made available at Glendale Community College. I don't know of its origins.
The glaze is a copper+rutile matte, which is very active and semifluid at cone 10. I would not consider it to be food safe. One of the active fluxing raw materials in the batch recipe is Gerstley Borate, which is no longer widely available. The glaze needs to be applied very thinly, or it will run. Yes, matte glazes can run, and this one does so very easily.
I will look for the recipe--I don't know if I still have it.