G-Shock "CasiOak:" Why it's Hot and a Rundown of the Collection

Japan’s Casio, renowned as the producer of the world’s first portable electronic calculator, released its first watch, the quartz-powered Casiotron, in 1974. But it wasn’t until 1983 that the electronics giant really made an impact on the timepiece world with the introduction of the first G-Shock. Conceived by Casio engineer Kikuo Ibe, who had experienced the loss of the beloved pocket watch his father had given him after he accidentally dropped it on a hard floor, the G-Shock was positioned from the beginning to be the world’s toughest watch, and the first to use urethane rubber in its construction.

From the original DW5000-C (recent version pictured above), with its rectangular case, all-digital LCD timekeeping display, and quartz movement with 10-year battery life, sprang an extensive family of G-Shocks, which by the time of the model’s 40th anniversary in 2023 would include both digital and analog-digital models as well as a variety of high-tech case materials. In 2019, the G-Shock family tree added a branch that made fans of a certain type of high-end sport-luxury timepiece stand up and take notice — namely the so-called “CasiOak” models (below), whose roots, it could be argued, reach back not only farther than the first G-Shock but even farther than the Casiotron.

It was a Swiss luxury watch, as groundbreaking in its own way as the G-Shock, that ultimately paved the way for the modern product family that we spotlight here. In 1972, two years before Casio threw its hat into the timepiece ring, venerable Swiss manufacture Audemars Piguet took a bold gamble on a model called the Royal Oak, its own first attempt at a fusion of sport watch and dress watch elements. The brainchild of visionary designer Gérald Genta, the Royal Oak was noteworthy for its radical-at-the-time signature feature, an octagonal-shaped bezel with visible screws, and for its smoothly tapering steel bracelet that integrated tightly to the case. (Click here for a deeper dive into the Audemars Piguet Royal Oak, below, and its impact on the watch industry.)

The watch’s design language, albeit not universally embraced by the market at first, would prove to be immensely influential: the same decade saw the debut of models like the Patek Philippe Nautilus (also designed by Genta), Girard-Perregaux Laureato, Tissot PRX, and Vacheron Constantin 222, the aesthetic forerunner of the modern Overseas collection. The popularity of this new style later exploded in the 1990s and into the 21st Century, and the 800-pound gorillas of the category — the Royal Oak and Nautilus — became victims of their own success, with supply perpetually unable to meet demand. Stepping into the breach to fill that demand have been brands like Bell & Ross, with its BR 05, Chopard with its Alpine Eagle, and Tissot, which resurrected the PRX (below) as an affordable alternative to the Royal Oak, the Nautilus, and their pricey brethren.

Even a Tissot PRX, however, will run you into the hundreds of dollars at a minimum, and more if you want one with a mechanical movement. And the Royal Oak “look” has so saturated the market that even enthusiasts with the most modest of means are seeking out something they can afford that ticks as many of those aesthetic boxes as possible. Here is where Casio, specifically the G-Shock brand — and yes, as of several years ago, Casio does consider G-Shock its own brand rather than a model series — steps in with its decades-long winning formula of making watches with an eye toward stylishly populist design, up-to-date technology, and mass-market pricing. 

The G-Shock GA-2100 debuted in 2019 and swiftly garnered the nickname “CasiOak” for its eight-sided bezel that was, to many, immediately evocative of the one on Audemars Piguet’s flagship timepiece, which was famously inspired by a vintage scuba diver’s helmet. The reference was far from a note-by-note homage to the Royal Oak; in fact, the design team behind it claims that the primary inspiration was the bezel on the earliest G-Shock models — which was, upon close examination, technically an octagon, albeit a much more rectangularly oriented one. It lacks some emblematic elements, such as the bezel’s visible eight-sided screws positioned at the cardinal points, for example. (Some might also point out that the side-mounted “bumpers” on the model are actually more reminiscent of the Patek Philippe Nautilus than the Royal Oak, even though this element has also been a longtime G-Shock staple.) But its robustly sized resin case, integrating into the segmented, bracelet-like urethane strap, and its predominantly analog-display dial (with some digital elements tucked into windows in the lower right) proved enough to catch the eye of many a mechanical-watch purist. 

At 45.4mm by 48.5mm in diameter, the resin case comes in at a somewhat surprisingly modest 11.9mm thick — surprising, because G-Shock models have long been famous for their chunkiness in addition to their array of built-in functions. The relative thinness of the “CasiOak” proved to be another factor that made it appealing to fans of luxury timepieces, who tend to lean toward a slimmer profile. All that said, the GA-2100 watches have plenty of appealing elements for the core G-Shock enthusiast, arranging an information-rich display in an analog-digital hybrid format. Two thick baton hands reveal the time on wide hour appliqués mounted on a sculpted flange, while an additional hand points to the day of the week on an arc-shaped indicator at 9 o’clock. Between 3 and 6 o’clock, the small LCD screen displays info including chronograph readouts, additional time zones, alarms, countdown timers, and a full auto calendar. Button-activated LED lights illuminate the dial for easy nighttime legibility, and G-Shock’s hallmark Carbon Core Guard case structure renders the watch water-resistant to an impressive 200 meters. The GA-2100 in all its various colorways and designs, is also a watch that just about any aficionado could afford, priced around $100.

With the GAB-2100 version of the “CasiOak,” released in the following year, G-Shock made a statement that it wasn’t catering only to penny-pinching wannabe Royal Oak owners but to its core audience of enthusiasts, who cherish the G-Shock’s continuing evolution on the technological side. The “B” in the alphanumeric reference number here refers to “Bluetooth,” and these members of the CasiOak family boast an array of smartwatch-style functionalities that come with pairing the timepiece with a devoted Casio Watches app on the owner’s smartphone. The owner can dispense with the ritual of setting the watch and adjusting the time, as all this can be accomplished wirelessly through the app, and the built-in Tough Solar technology utilizes light to constantly recharge the movement’s battery. The 9 o’clock display on the Bluetooth-equipped CasiOaks features indicators for mode and battery life rather than a weekday display. The Bluetooth and Tough Solar logos appear on the dial at 3 o’clock; below them lie the same digital windows as on the GA-2100 versions, with the same plethora of functions.

The list of features packed into the Bluetooth-enabled CasiOaks reads like a tech geek’s ultimate device wish list: a world-time function capable of displaying 38 time zones, plus UTC, or Universal Coordinated Time; calendar indications that will be accurate through the year 2099 without any need to reset for differing lengths of months or even leap years; a stopwatch that can track elapsed times, including lap times and split times, up to 24 hours and with an accuracy to 1/100-second; and a countdown timer that can be set for up to 60 minutes, to name some of the high-tech highlights. Also, like the non-Bluetooth models, the GAB-2100s include a button-operated “hand-shift,” a useful feature whereby the owner can move the analog hands out of the way in order to read information on the digital display. Adding all the Bluetooth options, incidentally, only adds about $50 to the cost; GAB-2100 CasiOaks start at $150.

If there’s been a predominant storyline around the G-Shock in the past five years or so, it’s been the family’s gradual but aggressive push into higher price segments and more elevated levels of luxury and collectibility. The CasiOak watches are no exceptions, following up other “Full Metal” versions of previous G-Shock models that substitute metals like stainless steel, rather than the brand’s traditional resin, for the core case material. The GM2100 (“M” for “metal”) debuted in 2021, and the Bluetooth-enabled GMB2100 followed shortly thereafter; the former models come mounted on the familiar G-Shock resin strap, the latter on steel link bracelets with exposed screws.

Both are just a smidgen smaller in diameter than the resin-cased models — 44.4mm x 49.3mm for the GM2100s, with a thickness of 11.8mm; and 44.5mm x 49.9mm with a 13.2mm profile for the GMB2100s. Sans Bluetooth on a resin strap, the GM2100 models retail for $200, while the “smartest” and most luxuriously designed models — the metal bracelet-mounted GMB2100s, including the gold-toned GMB2100GD-5A pictured below, command the highest price in the extended CasiOak family, at $550-$600. Bottom line? One of these watches likely won't pay for your kid's college tuition if you choose to resell it, but it also won't require you to take out a second mortgage or languish on an interminable wait list to purchase one. And you'll probably want to wear it. A lot.