I've been using Lustre Gel for almost a year and did not have good luck at all adding the gel in purple phase and firing on P3 because when I would fire all of the glaze would melt to the bottom and pool at the cervical edge. I recently read a post, saying that P3 was ok because of how the cycle worked, so I figured I would try again. My crown turned out really really shiny but has a melted appearance and literally all of my color, especially the blue, went straight to the cervical. I removed it, re-stained/glazed and placed it on the 10 min cycle that GC recommends. So just a warning, if you want to add a lot of color, be careful with P3 because it is easy to melt it all together...
Here was my end result... I'm loving her new smile! #8 Bioreference with e.max A2 HT and Lustre Gel for the stain and glaze.