Thanks Daryl, points well taken. Actually, this night sight isn't the typical 3/32", or larger diameter bead-it is quite fine and I'm guessing a near exact facsimile of the steel bead. It appears large in the blurry photo due to artifact.
I'll mic it and photograph it at some point. I agree that it shouldn't be too tough for a good gunsmith to duplicate it in steel. The ivory sight would appear fragile, but then again it has withstood the test of time.