Brian Roemmele via Quora:

Why is Apple moving to Zirconia Ceramics?

  1. Strength
  2. Radio Transparency
  3. Heat Conducton[sic]/Dissipation - with Alumina / Aluminum Nitride
  4. Scratch resistance
  5. Ease of manufacturing

The Apple Watch Edition Series 2 only comes in white, but it stands to reason a ceramic iPhone would come in both black and white. I’m a little surprised Apple would release the Jet Black iPhone this year rather than surprise us with a brand new color along with the ceramic housing.