Apple may in fact be ready to debut a sapphire crystal screen with the iPhone 6, but apparently in limited fashion.

According to CNET, one expert speculates that Apple will only release a 64GB version of the iPhone 6 with a sapphire crystal screen and charge an extra $100 for it. The material is more expensive to produce and takes longer to manufacture, meaning Apple may not be able to equip all its devices with it anyway.

Marques Brownlee displayed the scratch-resistance of a sapphire crystal screen with a model that was supposedly obtained from an early iPhone 6 mold. In a YouTube video, he took a knife to it to show just how much it could take.

Because of the time and money it takes to produce sapphire crystal, Apple has only used it to cover their camera lenses and Touch ID fingerprint scanner. That is widely expected to expand ever since Apple teamed up with GT Advanced to buy two sapphire factories in the U.S.

"We believe that Apple may upgrade the screen of the 64GB versions of the iPhone 6 to sapphire as an early market test to see consumer feedback for sapphire screen phones with the eventual intention of moving the whole product line to sapphire within 2 years (i.e., iPhone 7)," Gene Munster, an analyst with Piper Jaffray, said in an investors report released Tuesday, according to CNET. "We believe that the 64GB device could make up 30 percent of units if sapphire were an additional feature based on our prior survey work from the iPhone 5S launch, which suggests that 25 percent of buyers opt for the 64GB capacity."

The analyst also said he expects Apple to unveil both the 4.7- and 5.5-inch iPhone 6 at their mysterious Sept. 9 event, though he did not speculate on specific release dates for either. Munster did speculate on whether or not we will see the iWatch at the event next week, saying it as 50-50 either way.