I saw an amethyst one attributed to Rihiimaki somewhere online too Robbo (probably an assumption based on the similarity to the carafe you mention), but consensus here on the board was that it wasn't Rihiimaki. Quality is fairly reasonable, the glass is not as thick as the M&S vase but certainly thicker than the Eternalle one. It has some wear to the base - it doesn't appear to be very new, but no clues as to maker on it.
Peter, thanks for clarifying and thanks to Gareth for the contact details for Eternalle. It seems they are an importer from the range of stuff I've seen with their branding on it.