Holy moly!! From the Nokia support forum:
Lumia 930, a few bugs/issues/defects - Nokia Support Discussions
I just want to let you all know this simple workaround for the purple tint issue on Lumia 930:
"We have been made aware of an issue where the displays on a limited number of Lumia 930 units are exhibiting purple discolourations. We are currently working on a software update that will deliver improvements.
In the meantime, affected customers can address the situation by performing the following steps:
Go to Settings > Brightness and set brightness setting to “Automatic” and “Medium”
Find a dark area and turn the display off and then on by pressing the Power button twice
Go to Settings > Display and then click on “Brightness Profile”
Increase the brightness by moving the slider to the right, which will remove the purple tint from the grey bar on the bottom of the UI."
WORKS!!