Okay, this is a piece that I pulled out of a box of Caithness weights. IT's the only one not labeled. and I have no idea why I put it into that box originally. Does it feel like Caithness? it has the classic cutoff window, but there are a few things, that make me think NOT Caithness.
1) It has a lightly iridized surface, except the view window of course. I don't think of Caithness, and iridizing weights together.
2) the inner glass is more of a thick mound, swirled yes, but not translucent like I think of with Caithness.
3) It uses some dichroic glass on the inner swirled mound, and again, I don't think of Caithness, and dichroic glass generally.
It could have been a one off, a sample of something they chose not to make perhaps.