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As summer draws to a close and most people are daydreaming about Labor Day picnics and feeling back-to-school jitters, the tech community is thinking about next month’s Apple event.

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Reuters / Yuya Shino

At the event, which Re/code reported will be held on Sept. 9, Apple is expected to announce its newest iPhone. Bloggers have dubbed it the iPhone 6. The rumor mills continue to churn out lists of features that the phone will offer, but the one that keeps cropping up is about this new phone’s screen.

Will it be bigger? Heck, yeah. Thinner? Of course! Lighter? You don’t even have to ask. Will its home button moo whenever you press it? (Crickets.)

Most intriguingly: Will its screen be made of sapphire rather than glass?

It remains to be seen which (if any) of the rumored features this rumored phone will include. But that sapphire thing is pretty interesting because we smartphone owners don’t know a whole lot about the materials that make up the shiny surfaces on our devices.

To learn more, I talked with sapphire makers, like Kyocera, and glass makers, like Corning. Below, I compiled five questions and answers so you’re a little smarter about what’s breaking when you drop your phone on concrete.

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1. Wait — a phone’s screen can be made of sapphire? Isn’t sapphire blue?

The sapphires we’re used to seeing in fancy rings and necklaces contain trace elements — like copper, magnesium or iron — mixed with the mineral corundum. This combination produces a blue hue or another color, like purple or yellow.

Synthetic sapphire, made by machines, is created in a controlled environment where no impurities reach the mineral. Therefore, the sapphire is clear.

2. What’s wrong with using the phrase “sapphire glass” when I make up rumors about the iPhone 6?

Sapphire isn’t glass, or silicon dioxide; it’s crystal, made of aluminum oxide. Both are clear and are used on smartphones, but they’re very different. While glass includes a whole family of materials that can be altered and adjusted for different performance results, sapphire’s properties don’t change.

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Corning Inc.

A prime example of morphing glass is Corning’s Gorilla Glass. The original Gorilla Glass was found on the original iPhone in 2007. A second version came out in 2010, followed by Gorilla 3, which came out in 2013 and is found on the Amazon Fire phone’s front and back, along with the Samsung Galaxy S5. Gorilla 4 is due out some time in the next four months, according to a spokesman for Corning. Each of these iterations improved in terms of strength and durability.

Long story short, use the phrase “sapphire display” if you want to sound smart in front of your techie friends.

3. What’s the advantage to a sapphire display?

Sapphire is known for its hardness, scoring a nine on the Mohs scale of mineral hardness behind diamond, which is a 10. It’s also known for being scratch-resistant. But it’s denser than glass, so it weighs more — a big factor in phones. And a spokesman for Corning told me that though it’s hard to create macro cracks in crystal, you do create micro cracks, and when it breaks, it always breaks along the crystal planes. For that reason, Corning thinks sapphire breaks more than its Gorilla Glass. (Go figure.)

A recent article in the MIT Technology Review pointed out a new, less expensive process that GT Advanced Technologies is using for applying a thin layer of sapphire to a surface — essentially laminating with sapphire.

Kyocera

4. Is sapphire new to the tech scene?

No, sapphire has been used in various technologies for decades. It takes an extremely high temperature to melt sapphire, so it’s useful in industrial products that can benefit from heat tolerance. One example is using sapphire as sleeves for bright lights that burn very hot.

Corning, now known primarily as a glass manufacturer, was a sapphire manufacturer, but stopped more than 30 years ago because it was such an expensive material and the economics weren’t right for the company. Kyocera, based in Japan, has been manufacturing sapphire for 41 years.

When it comes to the iPhone, rumors keep pointing to GT Advanced Technologies as the supplier of Apple’s sapphire.

5. Can’t I already buy a smartphone with a sapphire display?

Funny you should ask. Just last week, Verizon released the Kyocera Brigadier with what Kyocera calls a sapphire shield. The phone is rugged, designed to withstand drops and scratches. And it’s waterproof. The Brigadier costs $50 with a two-year Verizon contract until August 17; after that it’s $100 under the same conditions.

Luxury smartphone maker Vertu also makes smartphones with sapphire displays, but they cost thousands of dollars.

Sapphire displays and new types of glass surfaces could mean fewer shattered phones, fewer replacements and happier users. Just don’t be surprised when your phone isn’t blue.




2 comments
Walt French
Walt French

Another source reported, “When we look at it, we see a lot of disadvantages of sapphire versus Gorilla Glass,” said [Corning’s Senior VP] Tripeny. “It’s about 10 times more expensive. It’s about 1.6 times heavier.”


Folks, that's perhaps another 2 grams, a 2% increase in weight, assuming Mr. Tripeny knows how Apple will deploy the sapphire, and that Apple won't use any extra hardness to reduce the weight of the rest of the monocoque-style case. Which is to say, worst case, because Mr. Tripeny wouldn't be spouting off about Apple designs unless he wanted his employer reamed for violating confidentiality.


Meanwhile, sapphire is about 10X as dense as Gorilla Glass. That means he thinks a sapphire screen would be thinner, maybe 0.7mm thinner. That'd reduce an iPhone5S's 7.6mm thickness by around 9%, a noticeable thinning.


But neither the hardness nor the weight is close to the REAL reason Apple must've gone looking, which is that up to a quarter (!) of all phones' screens get cracked, and that's both a big warranty expense AND a reputational black eye. I'll bet that the engineers actually went for a tougher screen that's not cracked nearly as easily in common scenarios where today's Gorilla Glass screens fail, and need to be replaced. The fact that we won't have to worry so much about some nuisance scratching because we put our keys into our phone pocket is a small side benefit.

OlavKiam
OlavKiam

This article could have been headlined "what's up with Sapphire displays anyway?". But no, putting the word "Apple" in there will just bait in more clicks. So lame. Visitor count going down? Here is one reason.

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