Characterising crystals and anti-reflective coatings

The watch crystal is, along with the dial, an essential part of the watch's image. Its brittleness, scratch resistance and transparency are important characteristics which are carefully inspected:

  • Crystal type inspection: sapphire, glass…
  • Crystal hardness measurement: Vickers, Knoop, Berkovitch instrumented nanoindentation
  • Crystal impact strength; ball drop test as per ISO 14368-3 (NIHS 61-13
  • Crystal static load strength as per ISO 14368-3 (NIHS 61-13)
  • Crystal scratch and resistance as per ISO 23160
  • Characterising anti-reflective coatings: optical characteristics, color, wear and scratch resistance, adhesion…