Smartwatches are becoming the next big thing and while there are numerous options out there already – there is one company that has yet to grace us with its presence in the market.

The Apple iWatch has been the subject of rumours for over a year, with the first story we published about it appearing in December 2012 but alas, the Cupertino-company has yet to reveal the much-anticipated device.

We have already rounded up all the Apple iWatch concepts but with the speculation picking up the pace and reports suggesting we are less than a month away from its release, we have decided to round up the rumours too so you have everything in one place.

READ: Apple iWatch pictures: The best leaked photos and concepts

Apple iWatch press event

Apple has sent invites for a press event on 9 September. The company's rumoured iWatch is expected debut alongside two new iPhones at the event.

It's been widely reported that the iWatch will show up at Apple's next event. But now tech website Recode, which has an impeccable track record when it comes to Apple rumours, has declared that Apple definitely plans to unveil a new wearable device, and soon. Recode previously claimed Apple wanted to introduce a new wearable in October, but the company has apparently moved the unveil date ahead to 9 September.

An October event might still be in the works however. Keep in mind Apple teased earlier this year that its autumn product pipeline will be the best in 25 years, so it could conceivably have enough new hardware to fill two events.

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Also, Apple's event invite simply shows the date and a line that reads: "We wish we could say more." The company usually gives away clues within its invites, so this reference to talking could be an improved Siri along with the release of the iWatch (which might be largely voice controlled).

READ: iWatch to show up at September event?

Apple iWatch release date

The first rumours surrounding the iWatch appeared way back in 2012, when Apple was claimed to be working with Intel on a Bluetooth smartwatch that would link up to an iPhone or iPad and feature a 1.5-inch OLED RiTdisplay screen. This variant was rumoured to be in an advanced stage at the time and was expected to launch in the first half of 2013. Needless to say, that never happened.

Bloomberg then claimed in March 2013 that it would arrive in the autumn of 2013, with the ability to receive incoming calls, view maps and record health data.

Ming-Chi Kuo, an analyst at KGI Securities later released a report predicting the iWatch was suffering from hardware and software issues so its release date was being delayed until 2014.

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On 3 June 2013 Apple is said to have filed an application for trademark of the name iWatch in Japan, but it was reported that the brand is already trademarked in the US, UK and China.

Apple iWatch display

The 1.5-inch OLED display claimed by Chinese website TGBus to be the screen for the iWatch back in 2012, was supported by Taiwanese newspaper Economic Times in May 2013, when the paper claimed trials and testing was ramping up. The report suggested Apple was furthering its testing by shipping 1,000 trial units to manufacturer Foxconn and was looking to use 1.5-inch OLED panels.

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When predicting the iWatch wouldn't arrive until the second half of 2014, analyst Kuo also suggested the device would feature a 1.5 to 2-inch display from a Japanese or Korean supplier. Similarly, Reuters reported, citing anonymous sources, the iWatch will sport a 2.4-inch display that is "slightly rectangular".

More speculation surrounded the display of the iWatch when an iWatch patent was filed in the US giving the impression that the device could come with a flexible screen.

Apple iWatch design

The New York Times reported in February 2013 that Apple was experimenting with a wristwatch made of curved glass that would operate on iOS and "stand apart from competitors based on the company's understanding of how such glass can curve around the human body". The iWatch design was originally rumoured to look similar to the sixth-generation iPod nano. (The image below is a concept.)

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Bloomberg also chirped up in February last year with a report claiming the iWatch project was in full swing, with over 100 people working on the device including Apple's senior director of engineering, James Foster, and another senior executive, Achim Pantfoerder.

It was then reported August last year that Apple hired Nike FuelBand consultant Jay Blahnik to work on the iWatch, which followed on from the Financial Times claiming people familiar with Apple's plans for the wearable device had said Apple has begun to hire "aggressively" for the project in recent weeks. AllThingsD and 9to5Mac both speculated that Blahnik joined the company's wearables team to work on a watch or wristband-type product.

Apple iWatch specs

Apple is expected to ditch Corning Gorilla Glass in favour of sapphire, a tough-as-nails material. The iWatch could therefore sport a sapphire display.

Rumours have also indicated the iWatch would need a processors that's both speedy and small, possibly along the lines of the 1.2 Qualcomm Snapdragon 400. That's the same chip found inside the Samsung Gear Live. Many rival watches also feature at least 512MB of RAM and 4GB of internal storage, so Apple would have to match those specs if it wants to launch a competitive product.

Apple's iWatch has been speculated to include more than 10 sensors ranging from an accelerometer, gyroscope, and altimeter to compass, heart-rate monitor, and pulse oximeter. These sensors would help it to become a full-fledged tracking device for fitness.

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Apple has also patented a small, curved battery design that could land in the iWatch. After all, components need to be tiny in order to fit into the wrist wearable. Speaking of batteries, Apple has reportedly landed a wireless charging coil supplier in China. The iWatch could therefore support wirelessly charge through magnetic induction.

Apple iWatch software

The iWatch will most likely run a version of iOS 8 and incorporate Siri, so that Apple's personal assistant can head your every beck and and phone call, according to several reports. The wearable is also expected to pull both iMessages and SMS texts from your iPhone as well as alert you of upcoming calendar events and reminder tasks.

Due to the several sensors expected to be included in Apple's wearable, it's safe to assume the iWatch will work with the company's HealthKit for iOS 8 that debuted earlier this summer. Coming in two parts, HealthKit and Health, the app will work with third-party apps to pull together all the health-related information that is being pulled in by the various apps people are using, rather than leaving the data siloed as it currently does.

The system will be able to capture and track numerous bits of information like weight, heart rate, calories burned, and even sleep allowing you to monitor your health without having to switch to a different app that you are currently using (as long as it supports the new features).

And finally, tech website Recode claimed recently that Apple's HomeKit for iOS 8, which the company previewed earlier this summer as a way to tie together smart home electronics, will work with rumoured iWatch. Presumably, if true, you could then use your iWatch to trigger smart light bulbs, door locks, or thermostat settings.