To the OP,
You are correct in that the collar and the threaded section/insert are 1pc.
As long as your intended ring-work isn't outrageously long, you can turn down the collar and install your rings.
If your shaft has a single blk. collar, it's approx. .470/.480" long.
If your intended r-work is shorter than that, you'll lose the difference in the OAL of the shaft if you want an exact match. If your r-work is close to .480", you won't.
If your intended r-work has a blk ring on top, you can leave that thickness on the top of the current collar and work back from there. Lotta 'ifs' huh?
You should be able to get a decent match without losing shaft length.
Mr. Wynne is correct in that you might want to consider sending the shaft to the builder of the cue. Since no pic, I gotta guess but if the deco-ring on your cue is done via CNC, the builder has the program and actual mtrls used also.
Post a pic. I may be able to help you further with this.
I don't know Eric, I don't know that I'd want to LET just anybody do this.:wink: