QUESTION: Labial piercing and ring gauge

Greetings:

I have one of those questions that is probably easily solved by
someone "in the know" but a perplexing quandry to the uninitated.

In the book "The Story of O", the main character recieves a labial
piercing that involves a sort of ID disk attached to the end of a
small chain which is then anchored to a ring pierced thru her labia.

My question is: how does one make such a think work in reality?

In other words, is there piercing jewelry that can be used to
accomplish this?

The only genital piercing jewelry that I have ever seen aren't
complete rings, but rather open "captive bead" type rings. I suppose a
chain could be slipped over the ring before the bead was put in
place.....but it seems that would make the anchor ring asymetrical and
the chain would get hung up on the bead. Furthermore, the bead/rign
would hardly be a permanent attachment.

Then there's the question of where to make the piercing and of what
gauge (if such an anchor ring even exists). The guage couldn't be too
small (narrow) or it wouldn't support the chain....but not too large
(wide) ir it wouldn't be suited to labial tissue. And then again, I
assume that the piercing site shouldn't be too close to the edge of
the labial otherwise the weight of the chain itself my cause it to
tear or rip out. (Though now that I think about it, the chain itself
doesn't need to be of a heavy guage...a light "charm bracelet" chain
would probably work without adding too much weight...okay, one problem
solved -- I suppose)

Has anyone out there had any experience with such a piercing regime?
Are there any informational websites that address such a piercing?

Any and all assistance appreciated.

Thanx!!