I like the idea that it must be Lead crystal. It does look slightly different to some of the wobbly base ones that were flooding the market. I guess it boils down to the sellers like to use the name Ysart. Grinding down the base a bit could be done at any time and would stop the wobbling and shelf scratching.
I am happy to add a section to Scotland's glass showing any number of these badge weights, if we can also include any documented makers - plus notes about all of the controversy, at least it will help people to make more informed decisions. I have one, packed away at the moment, that I would say is clearly not Ysart. But in order to put up such a section I will expect a reasonable number of examples... at least ten, preferably 50+. I do not have the time to track them down myself so a volunteer/s to gather the images and write up the notes would be helpful.
Images for each should be
1. Top view.
2. Side view.
3. Base 20-30° angle, to show base shaping.
4. Detail view, to show bubbles on badge
5. Other views to highlight features, colours of ground and technique of ground - as appropriate
On a white or neutral background to help compare the colour and transparency of the metal.
Measurements to 1/8th inch (1mm) accuracy and weight. SG if possible. UV long and short, if possible.