Repairing Fenton glass decreases its worth, as collectors consider Fenton glass that is in its original state and in mint condition more valuable. Any chips or blemishes that are present or covered up through repairs can decrease the glass' worth. Even bubbles in the glass can decrease its overall value.
Fenton glass manufactured prior to 1950 or from a limited line is the most valuable, especially if it is in pristine condition and unaltered in any way. Collectors require Fenton glass bells to have the clapper fully intact and free of any damage or repair work. The ware and mold numbers are present on most Fenton glass pieces, which can otherwise be difficult for collectors to identify as being authentic, as many Fenton glass imitations exist.