thanks Chris........it was mostly the shape that first got me thinking of W/Fs., but looking at the pix in Jackson the amethyst showing there (page 123) seems a different shade to this one. There is, however, a piece of amethyst in the same book (the large experimental vase on page 136 - plate 149) that is a deeper shade, similar to this piece. I think Christine is correct in saying that in my piece the ribs don't spiral, at least not until they get to within an inch of the rim, then they do lean round a little.