Sapphire glass is once again being rumored for the unannounced but highly anticipated iPhone 6 and iWatch. Apple's $700 million investment in a sapphire manufacturing facility with partner GT Advanced Technologies is also once again being highlighted as part of the rationale for the move. However, not all versions of all devices might get the sapphire glass according to the Wall Street Journal:

Apple is considering using sapphire screens in more-expensive models of the two new, larger iPhones it plans to debut this fall, if it can get enough of the material, people familiar with the matter say. Some analysts expect Apple to charge more for the phones than previous new models, because of increased component costs.

via: Apple may use sapphire screens on both iPhone 6 models, iWatch | iMore