"We're not quite finished yet. We have one more thing," began a giddy Tim Cook, Apple's chief executive, during the company's overnight event.

Cook had just finished unveiling two new iPhones, yet it was this addendum to the presentation that had the usually cool and collected Apple veteran breaking an ear-to-ear grin.

"We've been working incredibly hard for a long time on an entirely new product. I am so excited and so proud to share it with you.

"It is the next chapter in Apple's story."

Cook then presented to a riotous crowd the company's first wearable, the Apple Watch, a smartwatch with a square watchface, redesigned operating system and a number of unique features.

Digital crown: The iPod wheel for the smartwatch

Navigating Apple's Watch is done through a rotary wheel on the side, which zooms in/out or pans the page. Pressing the digital crown returns to the homescreen, while it can also be used to initiate Apple's Siri personal assistant.

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"What we didn't do was take the iPhone and shrink the user interface and strap it on your wrist. The display is too small, it would be a terrible customer experience," said Cook.

Coating the Apple Watch is Sapphire glass, which is second in durability only to diamond. Force Touch technology allows the retina display to recognise differences between a tap and a press.

Two Watch users can send custom emoticons, draw images on the Watch's screen or even have the beat of their heart sent as vibrations.

"We created new and intimate ways to communicate directly from your wrist," said Cook. "It's also a comprehensive health and fitness device."

Four translucent sensors rest on the underside of the watchface. They monitor heart rate and, by working with an accelerometer, GPS and Wi-Fi, record daily activity and exercise.

Additional uses according to Cook include remote functionality for Apple's TV, as a remote viewfinder to take photos and as a Walkie Talkie.

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The Watch has been designed to work as a companion to Apple iPhones. Watch-friendly versions of Apple applications have been made for the wearable, while Apple has shown diligence in compensating for the lack of a keyboard.

Apple's Watch can automatically formulate responses for text messages. The wearable will draft a reply based on keywords. Alternatively Apple's Siri personal assistant can be used to dictate a response.

The Watch is powered by a compact S1 computer chip purpose built by Apple. Cook claimed Apple had placed an entire computer's architecture onto the S1 chip. Also on board is a 'taptic' sensor responsible for vibrations and, according to Cook, a waterproof speaker. Inducted charging is used for charging.

Two sizes and three designs

Apple is manufacturing the Watch in two sizes, 38mm and 42mm. Three smartwatches will complete the range, with the Apple Watch, Apple Watch Sport and the Apple Watch Edition, the latter coming in 18 karat rose or yellow gold. The watches will be further customisable with six different straps.

The Apple Watch is scheduled to be released next year. Local pricing remains unknown; however, prices start at $349 in the US.

Read our Apple Watch review