The speculation is building. Apple's (NASDAQ:AAPL) upcoming iPhone 6 almost certainly looks poised to sport this wild new technology. With the company's newly forged partnership with sapphire crystal maker GT Advanced Technologies (OTC:GTATQ) it's rumored that Apple is readying new devices that will sport sapphire crystal displays -- particularly the iPhone 6. As the typical fall launch timeframe for Apple's next-generation iPhone lineup approaches, a few videos have surfaced showing the impressive capabilities of the material. Could Apple's iPhone 6 display be nearly indestructible?

iPhone 6 concept. Design by Tomas Moyano and Nicolas Aichino.

Indestructible sapphire?
On the Mohs scale of mineral hardness, pure sapphire comes in at an impressive 9, making it "the second hardest naturally occurring material on Earth," according to YouTube tech reviewer Marques Brownlee. 

This sort of hardness enables sapphire to hold up against considerable efforts to damage it. One of the few phones confirmed to use a sapphire crystal display is the upcoming Kyocera smartphone. On YouTube, Koycera shows just how indestructible its "Sapphire Shield" is by comparing it to "impact-resistant glass" using a rock and a drop test. While the sapphire display holds up perfectly to attempts to scratch and destroy the glass, the impact-resistant glass fails both tests.

But while Apple's iPhone 6 display may be made from sapphire, it is more likely to be some form of a sapphire hybrid. A new video released yesterday on YouTube by Brownlee shows an alleged iPhone 6 display get scratched by sandpapers made with materials rated at hardness levels below sapphire's 9 rating. But the Touch ID home button used in the iPhone 5s, which Apple has confirmed uses sapphire, did not show any scratches from the sandpapers.

The alleged iPhone 6 display, however, did hold up considerably better to the sandpapers than the iPhone 5s. Brownlee suggests the iPhone 6 could use sapphire in its display but may not be pure sapphire. This would be in line with a patent filed by Apple last year of a hybrid sapphire-coated display, MacRumors notes. 

While a hybrid sapphire display may show less resistance to scratching than pure sapphire, there are advantages for Apple in using a hybrid as opposed to the pure sapphire display. As Brownlee showed in a previous video, the hybrid resisted every attempt to break the display by bending. And a pure sapphire cover, on the other hand, probably couldn't withstand this sort of bending. There's also a good chance the hybrid is more resistant to drop tests than sapphire.

A better material and key competitive advantage
If this really is the display for the iPhone 6, Apple has produced a winner. While the glass is subject to scratches from extremely hard materials, none of these materials are used in the hard items we carry in our pockets such as keys and knifes. Combining the display's resistance to scratches and bending, the display is nearly indestructible when it comes to everyday use.

Reports about whether Apple will use it across its entire iPhone 6 lineup are still mixed. Recently, speculation has turned form whether it will be used in the 4.7-inch or the phablet-like 5.5-inch iPhone 6, to a new report from NPD DisplaySearch asserting that the display will only be used in either the 64 GB version of the larger or smaller version, and not in the 32 GB versions of either screen size. NPD says this is due to the sapphire crystal display's high cost and possibly because of supply limitations with the glass also being used in Apple's rumored iWatch.

iWatch concept design by SET Solution. Image used with permission. Watch a video of this concept here.

Obviously investors would want to see this seemingly superior material used in as much of Apple's upcoming product line as possible. On the other hand, having it only in premium versions of Apple's next-generation iPhone lineup and the new iWatch product could serve as a way to upsell iPhone buyers and compel Apple users to give the iWatch a shot.

Best of all, as Fool senior technology specialist Evan Niu recently explained, it's not going to be easy for competitors to imitate this impressive feat Apple seems to have achieved with sapphire covers. In an increasingly competitive smartphone market, Apple's sapphire display could be the differentiating factor Apple needs to stand out with the iPhone 6.