Hi Barbara, The info. I have about this is all straight out of Lesley Jackson. Amethyst is an early colour - (it is an unusual shade, isn't it?), and if you look in the marks section at the back it says that between 1969 and 1972, sometimes this Maltese Cross prunt was used.
I would not have a clue if Michael Harris made this carafe or not, sorry!
Sometimes, with these more simple shapes, I get a feeling about a piece, that it might be, but only when I can see it "in vitro" and handle it. It's something about the way the hot glass has been worked, I think Peter paradisetrader summed it up when he said Michael Harris had an intimacy with the movement of the glass, that he worked with it rather than trying to impose upon it. (B. Cartland moment over!)