Apple is looking increasingly more likely to employ sapphire crystal screen technology on the rumoured iPhone 6, and that appears to be rubbing the current leader in mobile glass up the wrong way.

Tony Tripeny, executive at Corning (maker of the popular Gorilla Glass which adorns many smartphones), wasted no time highlighting sapphire's disadvantages during a Morgan Stanley Technology conference.

Tripeny raised several points surrounding the negative aspect of sapphire technology, "it's about 10 times more expensive [than Gorilla Glass]. It's about 1.6 times heavier. It's environmentally unfriendly."

There are also concerns about sapphire's opacity, which could potentially make the screen harder to view and Tripeny noted "it transmits less light which... means either dimmer devices or shorter battery life."

Not so tough

Coring reckons that its Gorilla Glass offering can also withstand more pressure than the sapphire equivalent - "about 2.5 times more pressure" in fact, although we can't put this claim to the test at the moment.

Apple will be aware of the issues surrounding sapphire glass as it's already used it to cover the TouchID sensor on the iPhone 5S and protect the lens on the iPhone 5, 5C and 5S.

The iPhone 6 is expected to arrive later this year so we'll have to wait and see if sapphire is the screen of choice for the Cupertino firm and whether it'll push the price of the handset up.

Via Cnet