Hi,
I think this possibly from the Lavender range of cut crystal by Caithness. I only have the 1992 catalogue with this range in and it doesn't show this exact shape, but there are very similar pieces.
I know these don't appear in the 1989 or 1993 catalogues, so 1990 or 1991 would be most likely to show this shape....., that's if it is a Caithness piece of course.
Best wishes,
Pete