It appears to be a classic Ascher cut center stone with stepped ( pyramid) baguettes in either side. It's certainly not a design exclusive to HW ( or anyone, for that matter) You could get a new one, or find an older one with a bit of sleuthing. It is a classic Deco design, although I think it was first made a bit earlier.
It's notoriously difficult to estimate the caret count with an Ascher cut because of the depth of the stone. A significant amount of the weight actually "hides" there, so the caret number may be higher than you would think, looking at the stone. HTH
Good luck!!