Apple’s Ion-X glass beats out the sapphire crystal glass in several categories in DisplayMate’s Apple Watch testing

BY Evan Selleck

Published 27 Apr 2015


There are three different tiers of the Apple Watch, beginning with the Watch Sport, followed by the Watch and finally the Watch Edition at the very top of the ladder.

One of the things that makes the variants different is the display technology. Specifically, the Apple Watch Sport boasts an Ion-X glass screen, while the Watch and Watch Edition both feature Sapphire Crystal for their displays. Now, according to an in-depth report published by Dr. Raymond Soneira for Displaymate, both the display are rated as “excellent,” but Soneira also praises the Ion-X glass in several different categories, besting the more expensive Sapphire Glass.

One area that the Ion-X Glass ranked higher than the Sapphire Glass was large viewing angles and ambient light. While Soneira points out the strengths of Sapphire Glass, the tests used indicated that it distinctly affects the optical performance of smartwatch displays. On the other end of the coin, the Ion-X Glass did not have this problem:

While sapphire is incredibly hard and scratch resistant, the Lab measurements have demonstrated that it significantly affects the optical performance of (emissive) smart watch displays compared to glass, particularly in high ambient light and for large viewing angles. This behavior is very different from sapphire as it is used in traditional watches, which work by light reflection and not by display emission. In order to increase the use of sapphire for displays, the sapphire industry will need to modify the optical properties of sapphire without significantly affecting its scratch resistance and other mechanical properties.

Soneira does note that “Enhanced Sapphire” will alleviate this issue at some point in the future, but for now the reflected light on the higher-end screens could prove bothersome to some owners.

Soneira also praises the displays for their color accuracy, and says that Apple has “done a great job with the OLED display” on the Watch. The full report is available through the source link below.

[via DisplayMate]