Black Azurene is actually achieved using a very dark blue enamel powder in a sort of very concentrated misty texture - not unlike that of Ysart backgrounds, for the black, while Stuart Strathearn uses a deep reddy-amethyst, solid base colour.
Azurene was produced in both silver and gold foil and in gold alone.
Stuart Strathearn pieces are finished off with cut and highly polished rims, IoWSG has heat-finished rims.
In the Stuart Strathearn pieces, the foil tends to be wrapped around the middle part on the piece;
in IoWSG, the foil is more all-over - although pwts do often have a baldy patch on top.
The appearance of the foil is different too - in IoWSG, it is more finely broken up, it looks more delicate than Stuart Strathearn, it's not so "in-your-face", slapped on.
I'm fairly positive your pwt is IoWSG, but the cylinder is Stuart Strathearn.