It comes as 4.7-inch iPhone production is expected to star to start next week, with the larger 5.5inch version set to start three weeks later.
sapphire is a hard, transparent material made of crystallising aluminium oxide, produced at high temperatures.
As the material is heated, it forms disks that can be sliced using diamond-coated saws.
These round disks are ground into shape, and polished, to become glass.
The technology is traditionally used in watch displays because it is thin, super-strong and scratch resistant.
Apple already uses sapphire crystal in the Touch ID fingerprint scanner on its latest iPhone 5S and to protects the phone's camera.
As a result, sapphire glass could potentially replace Gorilla Glass currently used in most high-end smartphones.
These round disks are ground into shape, and polished, to become glass.
The technology is traditionally used in watch displays because it is thin, super-strong and scratch resistant.
Apple already uses sapphire crystal in the Touch ID fingerprint scanner on its latest iPhone 5S and to protects the phone's camera.
As a result, sapphire glass could potentially replace Gorilla Glass currently used in most high-end smartphones.
The latest report appears to contradict earlier claims the larger 'phablet' sized iPhone 6 won't ship until 2015,
Analyst believed the firm has hit problems manufacturing the handset's case and screen, and would now only launch a 4.7inch version this year.
The handset is expected to have a new 'indestructible' sapphire glass screen.
KGI Securities analyst Ming-Chi Kuo said the problems were found while Apple produced the smaller handset, according to 9to5mac.
'Production bottlenecks on 4.7-inch iPhone 6 center on the yield rate of in-cell touch panel and metal casing,' claims
'As in-cell touch panel becomes larger in size, the edge of the panel may become insensitive to touch.
'Meanwhile, under new manufacturing process for the iPhone 6 metal casing, color unevenness is an issue.'
According to 9th5mac, Kuo says that these problems become more complicated with the larger 5.5-inch iPhone 6.
'As these new concerns are coupled with earlier concerns about the production of sapphire displays for the larger device, the analyst believes that the 5.5-inch iPhone 6 may not launch by the end of 2014, or may launch after October in very limited quantities.'
Kuo also believes that Apple will cut the prices of the iPhone 5s and iPhone 5c alongside the launch of the 4.7-inch iPhone 6.
Previous leaks have claimed the handset will have a virtually indestructible screen made of sapphire.
A YouTube videomaker claims to have acquired one of the screens - and has subjected it to a barrage of abuse, from stabbing it with a knife and keys to bending and twisting it.In the video, the screen emerges totally unscathed - raising hopes is could lead to a far more resilient handset from Apple.
Marques Brownlee, a popular YouTube host claims to have got the screen from well known Apple leaker Sonny Dickson, who recently made his own video showcasing the screen.
Models of the new iPhone 5s (front) and iPhone 5c (back) are on display at the Apple Store in Berlin. Kuo also believes that Apple will cut the prices of the iPhone 5s and iPhone 5c alongside the launch of the 4.7-inch iPhone 6.
In the video he can be seen bending and twisting the screen.
'I slowly realized there is absolutely no way I can break this display under my own power,' he said.
'The worst blemish on the surface was actually my fingerprint marks and the dust from handling it so much.'
The glass is also extremely high-quality, Brownlee noted: 'There’s absolutely no color shift while looking through the sapphire glass.'
It is claimed the screen is made from sapphire crystal.
Apple already uses a small amount of sapphire glass for the 'Home' button and camera lens in the iPhone 5S, but the rest of the current iPhone front display is made of Gorilla Glass.
The new glass display is 'paper thin,' Brownlee said in his video.
Brownlee shows his screen measures 4.7 inches diagonally, keeping with rumors that Apple will release two different-sized iPhones this year: A 4.7-inch model and 5.5-inch one.
Reports Apple was experimenting with sapphire displays began last year, yet sources claimed at the time Apple found the technology ‘infeasible.’
This was because sapphire glass is more expensive to produce than normal screens.
However, Apple recently announced plans to open a mineral plant in Arizona with sapphire glass experts GT Advanced Technologies.
The facility is expected to employ around 700 people to manufacture sapphire crystal and sapphire glass, and this technology could make its way onto the screens of the next iPhone.
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