I'm not sure what you mean by "retire" the stem, but if you mean make a replacement, that's certainly possible to have done. Boiling the stem in bleach is a new one on me, but whoever did that hasn't got a clue. More than likely, your stem is made of Vulcanite, a form of hardened rubber.
Assuming that the stem is merely discolored and still fits into the mortise of the shank, you can restore the finish with the application of a little elbow grease. You can buy a set of micromesh pads at a local hobby shop, or online. You use the pads, starting with the coarsest grade to remove the discoloration, and follow by sanding with succeedingly finer grades to achieve a polished surface.
If you want to have the pipe restored, there are a number of repairmen who can make you a stem and minimize dings to the surface of the pipe. Georged, a member here, is a superb repairman.
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