How long to make a purple jar?

[wulfdog]

I was wondering, does anyone know how long it takes a fruit jar or bottle with the magnesium in it to turn purple in the sun? I have some older fruit jars that I would like to turn, but before I start I would like to know how long it will take and if there is a way to speed up the process.

 

[Harry Pristis]

Do a search of this forum over the past 6 months or a year to find plenty of discussion of "manganese" and "purple glass" and "sun-colored amythest."