An interesting characteristic of colorless glasses which contain manganese dioxide as a decolorizer is their tendency to turn different shades of purple when exposed to the rays of the sun or to other ultra-violet sources. ... This changes the manganese compound into a form that causes the glass to turn purple.
As far as I understand the concept, I don't think that's a true possibility. Basically as the glass industry grew they made better materials for the clarity stability and quality. I think that if they were importing sand, that alone would be very costly and the general population would have been hard pressed to afford. The fact that I've seen ball and other fruit jars be "nuked" to force the color change in order to get premium prices for average jars otherwise, leads me to think that it was a mass use material for a while and the potential for a lot of products to change in uv exposure is a neat but novelty thing. If it is true purple or made originally as purple then I see the expenses, but to have a $2 jar go to $200 because it's claimed as a purple Mason or what not is an absolute shame.
Thank you for the info. I had heard WW1 was a cut-off date for purple glass from sun exposure. Thanks!
It was obtaining manganese that was the issue. War use and other factors. Harry's reply says it better than I ever could have.
