Apple Watch Sport's Display With Ion-X Glass Outperforms Sapphire Models in Bright Lighting

Although there has been much comparison of the scratch-resistance and weight differences between the two Apple Watch display cover options -- sapphire crystal and Ion-X glass -- not much has been scientifically tested regarding each model's reflectiveness. A new report by DisplayMate out today, however, shows just how much lower reflectivity and higher contrast there is on the Apple Watch Sport's Ion-X glass compared to the higher-end Apple Watch models with sapphire.

As DisplayMate points out, the two models have identical OLED displays internally, but thanks to the different outer coverings, the different models react uniquely in bright light situations. In summary, the site found that the Apple Watch with sapphire crystal display reflects 74 percent more ambient light than the Ion-X glass of the Sport model. The two displays behave almost identically in dark environments given the low levels of ambient light available for reflection.

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Photo comparing Ion-X glass (left) and sapphire crystal (right) taken at 2,000 lux, which equates to moderate outdoor lighting
For the Apple Watch Sport with Ion-X Glass we measured the Screen Reflectance to be 4.7 percent, while for the Apple Watch with Sapphire we measured 8.2 percent Screen Reflectance, which is 74 percent higher than with Glass. Both values are about 0.6 percent higher than just pure sapphire and glass alone, indicating that Apple has done an excellent job in optically bonding both the glass and sapphire to the OLED display without an air gap.

The 74 percent higher Reflectance of the Apple Watch with Sapphire means that its screen will reflect almost twice as much surrounding ambient light as the Apple Watch Sport with Glass. And it takes surprisingly little ambient light for that to make a significant visible difference…
Starting in the dark at 0 lux, DisplayMate increased light levels in successive stages of testing to discover the contrast ratios of each screen under increasingly stressful lighting situations. With both displays set to their maximum brightness, at 500 lux ("mid-range indoor ambient lighting") the display contrast ratios had fallen from 100 to 64 for Ion-X and 38 for sapphire, illustrating the distinct visibility advantage for the cheaper model. Jumping to 2,000 lux ("moderate outdoor lighting in the shade or an overcast sky"), the ratios drop to 17 and 10 for Ion-X glass and sapphire, respectively.

Screen Shot 2015-06-29 at 11.16.08 AM
Chart comparing various aspects of reflectivity between the two displays

For a full-on sunlight measurement of 10,000 lux, the Ion-X glass display contrast ratio fell to 3 while the Sapphire Crystal came in at just 2. So, while the Sport's display proves to handle moderate outdoor sunlight much better than the sapphire display, both are significantly impacted by harsh, direct sunlight.

Higher reflectivity and lower light transmittance were highlighted as challenges for Apple amid Apple's failed partnership with GT Advanced Technologies for sapphire production and rumors the iPhone 6 would include a sapphire display cover. Recent advancements in sapphire production technology may, however, overcome those difficulties, with future generations of products able to use sapphire that has better viewing characteristics than glass while retaining sapphire's advantages of high scratch resistance.

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Top Rated Comments

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60 months ago
Let the whining BEGIN!
Rating: 11 Votes
60 months ago
The clarity from the lack of reflection will be negated by all them scratches! :p
Rating: 11 Votes
60 months ago
WORKAROUND: Don't aim watch face at the sun.
Rating: 11 Votes
60 months ago
My Apple Watch Edition has the same problem in bright sunlight. It's annoying, but overall I value the social status I acquired with my purchase more than worrying about trying to use it.
Rating: 11 Votes
60 months ago
IF I were considering purchasing and Apple Watch, I'd naturally go for the Sport model… but only based on it's lower price point. (The better on-screen contrast with the Ion-X glass is an added bonus.)
Rating: 9 Votes
60 months ago

My Apple Watch Edition has the same problem in bright sunlight. It's annoying, but overall I value the social status I acquired with my purchase more than worrying about trying to use it.


lol
Rating: 9 Votes
60 months ago
I'm waiting for...

Ion-X glass causes more battery loss!
Rating: 6 Votes
60 months ago
Not entirely surprising. The Sport model is the entry level device (largest percentage of units solid), but moreover, the one that would see heavier use outdoors due to its intended use cases (exercise). In other words, screwing up the "lowest end model" would probably have the largest impact on profits -- anything other than excellent performance per dollar was simply not an option.

I went with the Sport to minimize my initial outlay (I expect I'll bite for next year's hardware). The fluoroelastomer bands have been super comfortable. Visibility even at the lowest brightness has been impeccable (despite lots of outdoor exercise). It also weighs substantially less (case is 30g instead of 50g). I like the idea of a Stainless Steel watch with a sapphire face, but not having worn a watch for nearly 20 years, the Sport has proven excellent. I may opt for a regular stainless steel watch in the future, when I've acclimated to wearing something on my wrist.

It's also satisfying my main use case: 8 pounds already lost, with 15 to go (3 lbs under my medically ideal weight).
Rating: 6 Votes
60 months ago
You're wearing it wrong?
Rating: 6 Votes
60 months ago

WORKAROUND: Don't aim watch face at the sun.


That's hardly a workaround when you're outdoors. You don't have to point it directly at the sun to not be able to read it properly...


For what it's worth, I can hardly read my Sport screen in bright outdoor light. I can just make out the time but not the weather or calendar complications. I still have to cover it with my hand to read it, so I doubt in day-to-day life it makes much difference whether you have the Sapphire display or not.
Rating: 4 Votes

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