[Rockhounds] Why does the color of some gems fade?

[Kreigh Tomaszewski]

Carol Carter-Wientjes wrote:
> 
> Hi Rock Friends,
> 
> Just back from a trip to Oregon and a first sunstone dig. What fun! We didn't find anything to retire on but did recover a couple lbs. of small schillers and a few little reds. Easy to see why people get hooked on digging them, count me in!
> 
> On to the question.....Why do some pink and purple gems fade? ie, rose quartz, Holley Blue, etc. How about carnelian too? Does it make a difference if they're heat-treated?
> 
> Looking forward to your comments on this, CaroL

Sunlight provides the energy needed to change crystal structure at the
molecular level and alter the properties of many colored crystals.

Kreigh