Why is my colored cap changing/ losing color?

Overheating will darken or dissipate the color of your cap quicker. As well as any oils on your fingers left on the cap with heat will cause the cap to lose color.

The PVD coating on the caps, especially the Rosium, is the thinnest coating, only a couple of microns thick.

Once heated, the bond of the coating can break down. This is why overheating will change the color drastically or discolor the caps. Regular heating shouldn't change it much.

There will be some patina development and minor changes. There will be minor changes in color irrespective of the heat source. You will notice the color change more drastically with a torch, it is less noticeable with an induction heater, but it still does happen.

Please watch the video below for more information. 

What is PVD coating? Physical Vapor Deposition