As the launch of Apple's latest iPhone looms, we look at the increasing volume of rumours around the iPhone 5S.

iPhone 5C Release Date 10 September
The iPhone 5S is expected to be launched on 10 September, with a better camera, processor, storage, a gold colour and a fingerprint sensor.

The iPhone 5S is set to be Apple's next flagship smartphone. Simply making this distinction highlights something which has never happened before - Apple is going to launch two models of the iPhone at once.

Unless Apple is trolling the entire internet and has created a highly elaborate ruse (blurry leaked pictures and all), Apple will launch a downmarket version of its smartphone - to be called the iPhone 5C - at the same time as it announces the iPhone 5S.

We will deal with the details, rumours and reports of the budget iPhone elsewhere, but for now let's focus on the iPhone 5S and the rumours coming out this week.

Release Date

The big news obviously is that sources have indicated that the launch of the next iPhone will take place on 10 September.

Sources with knowledge of the makker, speaking to AllThingsD, confirmed 10 September as the date for the launch. This is exactly one year since the launch of the iPhone 5 and as is typical for Apple, the event will be held on a Tuesday.

Apple is expected to launch two iPhone models at the event, but not much else. Reports suggest updated iPad and iPad mini models won't arrive until later in the year, and the much-rumoured/highly-anticipated/may-never-happen iWatch and iTV are not yet ready for prime time.

If Apple follows the pattern from last year we will see queues snaking around Apple stores around the world on the morning of Friday, 19 September when the iPhone 5S goes on sale.

Gold Colour iPhone

Bit of an odd one this. But it seems to have some leg, if respected Apple analyst Ming-Chi Kuo from KGI Securities is to be believed.

Kuo backed up an earlier report from Japanese blog Macotakara which first reported the rumour that Apple will offer the iPhone 5S in the traditional options of black and white, but also in the bling-bling option of champagne gold.

Gold colour option for iPhone 5S

While this will surely please all those who want their phone to match their jewellery, would you really want to be seen speaking into a gold brick?

128GB

Earlier this year Apple began offering the iPad in a 128GB configuration and so expectation is it will begin offering the iPhone 5C with the larger storage option too.

Currently limited to 64GB, many iPhone users who use their smartphone as a portable music player and to store photos and movies will welcome the option to upgrade.

In a note to customers Kuo agrees with the rumour about increased storage, but also suggests the iPhone 5S will be powered by a new A7 chip which will be based on ARM's 64-bit ARMv8 architecture.

Kuo says it would make everything more "efficient" and it would be a major step up from previous Apple chips which used 32-bit architecture.

The move to 64-bit architecture would allow the A7 chip to address more memory and make it better at running more demanding software.

Sapphire Home button

Like the gold option, this is a bit of an odd one. Again this comes from Kuo, who predicts that rather than the concave, plastic home button on current iPhones, the iPhone 5S will feature a home button made of sapphire which will protrude slightly from the front of the phone.

Not only that, the home button will have a finger-print scanner integrated into it. This is a rumour which has been circulating since before the launch of the iPhone 5 when Apple purchased fingerprint specialists Authentic for $356 million.

Kuo says the convex shape of the new home button would allow for the inclusion of the fingerprint sensor underneath, as that space is already occupied by the Lightning connector, speaker and microphone.

Larger F2.0 aperture camera

Finally from Kuo, he predicts Apple will significantly improve the camera on the iPhone 5S. He predicts the use of a larger F2.0 aperture lens which should dramatically improve low light performance - an area Apple has fallen behind the likes of Nokia and HTC in the last 12 months.

We have previously heard reports of dual flashes and Kuo agrees with this, though he fails to talk about the size of the sensor with rumours of 12 or 13 megapixels being the most widely reported.

iOS 7 Gold Master

And of course there is the software which will be running on the iPhone 5S. This will obviously be iOS 7 which Apple unveiled at WWDC in June.

iOS 7 Gold Master Due for Release 5 September
Reports suggest Apple will release the final version of iOS 7 - known as the Gold Master - on 5 September.

A report from BGR this week suggests the final version of iOS 7 - known as the Gold Master - will be released to employees and carriers on 5 September with developers getting their hands on it on 10 September.

However that report, based on sources, also suggested iOS 7 Beta 6 would be released next week, but Apple unexpectedly released it to developers on Friday (15 August), which could indicate that Apple is ahead of schedule with iOS 7.