All I really know is that Paul Ysart multi-layer Harlequin weights were:
- bubbles over single layer = Harlequin (implies single Harlequin)
- second layer with bubbles and "legs" reaching down to base layer = Double Harlequin
- third layer with bubbles and "legs" reaching down to second layer, whith "legs" down to base layer = Triple Harlequin
I have one example of what I call a "double-layer Aladdins Cave", and the base layer of canes are set immediately onto the dark coloured ground. So it looks like two layers but with the base layer consisting of both opaque "black" and cane bits.
The book on Perthshire Paperweights does not clearly show a profile view of any "Aladdins Cave" weight but talks about things like "two layers and a coloured ground". What that really means needs confirmation.