Question for the esperts

Hi all, I have been just lurking and learning a lot for the last
seveal months. My 11 year old son is doing his science fairs project
on quartz, amethyst and citrine and has done most of the research
himself. He has a question that he wanted me to pass on to all of
you. What kind of radiation is it that puts the extra spin on the
iron oxide ions in the amethyst crystal matrix that causes the purple
color? He was wondering if it was like X-rays or as I suggested was
gamma radiation or if it even mattered? He also wondered if X-ray
radiation would deepen the color of a pale amethyst. He has already
had some good luck with heat treating amethyst to turn it to citrine,
and the about the radiation would give him a more complete
project. He wants to do a good enough job to be able to go to state
level competion this year, so any help you can give us would be deeply
appreciated. You can contact him directly at or you can contact me at @lynnb
Thank you in advance for any help any of you can give us. Sincerely,
Lynn Bell