Here is the second of our recent 'European' acquisitions from antiques and collectables shops near our new home. It is a shallow flared bowl, 4.5cm high and just over 15cm in diameter (almost exactly 6 inches in the old money). The pontil scar is covered by an applied pad, which is finely ground concave, and the whole base including the applied pad is ground and polished. (There was a small air bubble under the applied pad, which has broken through with the concave grinding.) The lower (and hence inner) part is coloured with what I assume to be marvered chips, although it remains quite transparent. The upper (and hence outer) part is dense with fine aventurine but otherwise colourless or perhaps slightly amber (it is hard to tell with all that sparkly stuff) and it too remains transparent. The glass both inside and out has a slight crinkliness to it, which becomes more pronounced further out towards the rim.
Now my questions, of course: Who made it and when? In my limited experience, that style of base suggests Monart and the overall shape is similar to images I've found online. The generous use of aventurine is also consistent with that source. My doubt focuses on the light touches of colouring - any Monart I have seen has much denser use of colour.
Trevor