Over forty years ago Audemars Poguet introduced Royal Oak – a steel casual sports watch with the unique octagonal bezel. Royal Oak was the result of a design approach that emphasized robust aesthetic. It made stress on function by bringing the screws – parts that usually stay concealed – out into the open. Audemars Piguet rightfully claim that the collection was revolutionary: it inverted and subverted existing design conventions.

No longer a novelty, today the octagonal bezel and the screws appear a natural modelling choice – sports watches are aimed at function, and revealing mechanical parts that ensure function seems sensible. Yet from purely aesthetic point of view there is still something shocking in this design. And this is its real strength: it remains fresh even after all these years.

Initially offering basic hours and minutes variations, Royal Oak gradually evolved into one of Audemars Piguet's broadest and most versatile collections. Watches currently in production include such complications as power-reserve indicator, chronograph (split-seconds), dual time, perpetual calendar, tourbillon, minute repeater (Audemars Piguet specialty) – and a grand complication model that combines most of these into one timepiece.

However, regardless of the complication, the basic Royal Oak structure always remains the same. The power design (the bezel, the screws) is enhanced by two single-block massive lugs, followed by a bracelet that repeats the lugs' appearance, or by a leather strap. Eventually almost all Royal Oak models keeps the seductive industrial edgy-smooth looks.

Royal Oak's strong basics allow it take freedoms with secondary flourishes. The collection utilizes precious metals (white, pink and yellow gold), uses a lot of color (black, white, blue, yellow, grey, red) on its dials, all of which are embossed with a distinct cubic grid. Royal Oak avoids numerals – unlike Royal Oak Offshore – instead employing variously shaped indices (though small numbers appear on the subdials).

This design choice indicates another step towards simplification, and even abstraction; Royal Oak eschews representative symbols when possible, opting for intuitive, informal indexing. I think that this feature makes these watches especially personal, even private, as reading time can be done on a nearly subconscious level. The illuminated dices go well with the trademark “thermometer” hands – my favorite feature in the Royal Oak.

Royal Oak includes two radical models: the grand complication and the jewelry variation. While the former becomes an admirable time keeper with a set of usable functions, the latter veers more into collectible territory, sporting an unusual futuristic look that adds hundreds of diamonds on top of the industrial design. These two lines of watches widen the scope of Royal Oak, securing its place asone of Audemars Piguet's most accomplished collections.