Multi-layer transparent structures for electronic device housings

A housing for an electronic device comprising:

• a front cover member for the housing including:
• a first layer including a first chemically strengthened glass material having a first inner surface and a first outer surface, the first outer surface defining at least a first portion of an exterior surface of the housing and having a first compressive stress;
• and
• a second layer including a second chemically strengthened glass material having a second inner surface and a second outer surface, the second inner surface having a second compressive stress that is less than the first compressive stress;
• and
• a housing structure having glass sides and a bottom and defining at least a portion of an interior volume and a second portion of the exterior surface of the housing, the second inner surface of the front cover member coupled to the glass sides of the housing.

An electronic device housing comprising:

• a glass housing structure having sides and a bottom formed from glass and defining at least a first portion of an exterior surface of the electronic device housing;
• and
• a cover structure attached to the glass housing structure and comprising:
• a first glass layer having a first compressive stress profile with a first depth, the first glass layer defining at least a second portion of the exterior surface of the electronic device housing;
• and
• a second glass layer bonded to the first glass layer and having a second compressive stress profile with a second depth that is less than the first depth.