With speculation building toward Apple’s Sept. 9 announcement that...

With speculation building toward Apple’s Sept. 9 announcement that the iPhone 6 will have sapphire cover glass, uBreakiFix, a smartphone and tech repair company, ran a series of drop tests to determine sapphire’s durability, the company said. It found that though sapphire is “remarkably hard,” it’s also “remarkably stiff” and “quite brittle,” it said. Its bottom line: “This brittleness may equate to broken screens. Sapphire may not be the indestructible cure-all that many have claimed it is.” In one trial, uBreakiFix said, it drop-tested a Kyocera Brigadier smartphone, which has a sapphire display, and found the sapphire screen remained intact when dropped from as high as 6 feet because the phone’s raised perimeter bezel protects the screen. When the display assembly was removed from the phone and dropped on its own, the screen cracked with a drop from only 3 feet, it said. “Our conclusion is that sapphire alone will not equate to an unbreakable iPhone,” it said, though hedging. “We can’t say if an iPhone 6 with a sapphire screen will be more or less durable overall. Clever engineering and protective features may still create a very durable device regardless of the use of sapphire.” GT Advanced Technologies, the Boston-area company that reportedly is supplying Apple with sapphire cover glass for the iPhone 6, didn’t comment immediately.