Say, I want to find the list of users who have a silver harry-potter badge .
For non-per-tag badges, you can go to the list of badges, and click on a badge name, which takes you to a list of badge awardees.
But per-tag-badges are NOT on the list; so this approach does not work.
Now, if one knows the badge ID (which I do in this case), one can construct the per-tag-badge URL yourself.
However, I know the ID since I already have the badge and click on it from my own badge list.
How can I find the badge ID (or link) for a per-tag-badge?
Please note that "Look at a user who has the badge" is NOT a valid answer, as there may be zero users with the badge so far (e.g. Gold harry-potter badge has no users).