1999 D Roosevelt Dime With Copper Color 2.2g With All Copper Ridge

It looks discolored.

KK

The rim may be discolored also so that's why you're seeing "100%" copper...or it may have gone through reticulation where the CN layer was reduced...I know that this is done with silver but not sure copper. Lastly it just could have been a thicker core layer?

KK

Environmental Damage, not an error.

Hiya there. I was wondering what you did with your dime and what your final determination was of it? I'm only asking because I too, have found the same exact dime, year and mm, Thanks!

Note the tops of the devices are starting to show the original color back again. On a missing clad coin, the color remains red in color. If you carry it in your pocket for a week, the brown color will turn dark and the gray color will start to appear again.

Also note on the missing clad from one side, leaves the devices weaker, because of the missing clad from just one side. Also not the red color.
On a quarter, you can really see how this missing clad layer leaves a weaker strike from the missing single clad layer.

Also not the surface is not showing the dry look that coins found outdoors can have: