iPhone 6
The 4.7-inch iPhone 6 model scratch test in Marques Brownlee's new video.Screenshot from Marques Brownlee's Video

Amid speculations on the release date of Apple's upcoming flagship smartphone, iPhone 6, a report has suggested that the display of the 4.7-inch model might not have been made of sapphire crystal glass after a new test indicating that the iPhone 5s home button is harder than the next generation smartphone's screen.

It was earlier reported that both the 4.7-inch and 5.5-inch models of iPhone 6 might have a scratch-free sapphire crystal glass screen, which is unbreakable and second only to diamond in hardness.

In a video, YouTube user Marques Brownlee has put the screens of iPhones to torture test, rating the hardness of mineral by using the Mohs scale. He used two sandpapers – garnet that is rated 7 on the Mohs scale of 1-10, and emery rated 8 – to scratch the screens of the purported iPhone 6 and its predecessor. Surprisingly, scratch marks are much deeper on iPhone 5s screen that in its successor.

The uploader said that the Touch ID home button of iPhone 5s, which is made of pure sapphire glass, couldn't be scratched by the sandpapers but it is not the case with the 4.7-inch model of iPhone 6, indicating that the screen of the upcoming smartphone is not made of pure sapphire, as speculated earlier. He went on to say that it would not be wise for Apple Inc. to use a full sapphire screen because of cost and flexibility factors.

The test has indicated that the screen of the 4.7-inch model of iPhone 6 could be coated with sapphire or next-generation version of Gorilla Glass, as it is harder than the Gorilla Glass used in iPhone 5s but softer than sapphire.

It was earlier reported that both the small and large models of iPhone 6 would have sapphire glass display before a new report emerged that the mineral would be seen only in the 5.5-inch variant.

Brownlee had earlier showcased the durability of iPhone 6 screen in a video, scratching the screen with a pointed pocket knife and keys in vain. He also tried to break it by bending it using his hands and feet, but ended saying, "I can break this display under my own power." 

A user may not resort to stabbing or scratching the phone screen with hard materials like garnet or emery, or for that matter a pointed knife unless by accident, but most followers of iPhone 6 will be curious to know the material used in its screen following speculations around it.

The 4.7-inch model of iPhone 6 may come with a 1920x1080p (440ppi) resolution, while the larger model may feature a 2272×1280 (510ppi) resolution, according to KDB Daewoo Securities. It is expected to be powered by a 20-nanometer A8 chip (64-bit) processor, run on iOS 8 and come with an 8MP camera with several upgrades, including flash and Optical Image Stabilisation. Apple Insider reported, citing analyst Ming-Chi Kuo that the smartphones may feature low temperature polysilicon in-cell touch panels, Touch ID fingerprint security, NFC and metal casing, and Chinese analyst Sun Chang Xu has revealed that the device might feature sensors that can detect pressure, temperature and humidity.

The device is expected to hit the stores in the month of September though the exact release date is still not known. German website, ApfelPage claimed citing leaked internal documents of German wireless carrier Deutsche Telekom that it will be unveiled on 19 September, contradicting reports that it might happen in the first or second week of the month.

VIDEO: iPhone 6 Sapphire: Explained!

(Image Credit: Screenshot from Marques Brownlee's YouTube Video)