As you have a pontil mark you can be pretty sure the rim was tooled, otherwise it makes no sense. Fire polishing is used for thin walled glass. After cracking off it is set upside down on a gas burner which gets rid of the sharp edges. Thick walled glass would rather be cut off using scissors, then smoothed over by tongues. To do this you need to attach a pontil rod on the underside, which is subsequently polished out.