Yes, other clues would be good.
But I think the "3D creature" weights from the Caithness & Harland periods were all finished with a smooth polished base, or they had a neatly finished foot. And I think it is not possible to visually separate the Caithness examples from the Harland ones by normal visual aspects alone (unless a Harland one has an "H" cane).
I could, of course, be wrong in my belief. So ...
... Does anyone have an example of a Paul Ysart "3D Creature" weight that does not have a smooth polished base, or neatly finished foot?