[tynorf]

The interior has been aluminum, but the band around the outside has been stainless steel.

> Ceramic Shield front, Textured matte glass back and stainless steel design

https://support.apple.com/kb/SP875?viewlocale=en_US&locale=e...

[nailer]

Interesting. 13 mini is

> Ceramic Shield front, Glass back and aluminum (sic) design

https://support.apple.com/kb/SP847?locale=en_GB