Can you reverse sun purple in glass?

The sun purple effect is the result of the formation of color centers due to exposure to ultraviolet light. While thought to be charming in the past, it is now regarded as a defect by many collectors.

Theoretically, it can be reversed by annealing (re-heating) the glass. In practice, the chances are that the piece will crack or melt before all color centers are removed. For this reason, it is considered irreversible, and should be avoided.

Keep your Early American Pattern Glass out of the sun, and if you are a dealer of such, avoid the temptation to artificially purple your merchandise with UV lamps.