John's weight is indeed by Salvador Ysart. See my example of a roundels pattern on the same white and green striped powdered ground.
As with John's, mine appears tinted (in some light conditions) but not as obvious and strong as the Op's weight. I do have a couple of Ysart weights with a stronger purple tint but again not to the degree of the Op's.
I agree with Christine's comment about the "chappie". It is known that Salavdor Ysart had some sulphides from the former Scottish John Ford company. I have seen several examples of a Robbie Burns sulphide in Ysart / Vasart weights and one example of "a lady". The Op's sulphide seems to differ in its general appearance. And together with the degree of the tint, these are two points that make me hesitant about my "Ysart possibility". However, the colours of the chips in the ground of the sulphide weight are very similar to what can be found in some Ysart items.
How about the bubbles? I have not seen an Ysart weight in the "harlequin" (bubbled over chips) pattern that also has a sulphide. But there might be some. Normally, Ysart weights have either six or eight bubbles - and four in a few early "layered" items by Paul. So the sulphide weight with six bubbles cannot be ruled out as "Ysart". The way that the colours have been "pulled" into a sort of loop and looking like a "six-armed starfish" from the top view, is not something I have seen in Ysart work (so far).
What about the base finish. The more I look at it, the more I think it is "too heavy looking" to be Ysart. Salvador's hovering butterfly weights, and also his "upright flower" weights are often large but the bases usually do not show the features seen in the Op's weight.
And the general look of the "clear" dome? It seems to be heavily striated in a way that is "rougher" than striations I have seen in several Ysart items.
I am still keeping an open mind, but I now favour continental Europe. But the strong purple tint (excess manganese in the mix) is something I cannot be sure of. I also need to check a couple of books, when I can find them.
Any other readers have a idea or two?