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Among fans, the Casio G-SHOCK GM-B2100D-1AER is now only called “CasiOak” – although the watch will only be available at retailers from August 12th. Nevertheless, it has already earned a small icon status. At least at first glance, it looks confusingly like the Royal Oak, Audemars Piguet’s flagship. Will the all-metal Hommage watch be as exciting at second glance?

An homage to two watches?


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CASIOAK G-SHOCK GM-B2100D-1AER Edelstahl Quick Review

The 2100 series is more popular among true G-SHOCK fans than few other collections. Some time ago, the Japanese watchmaker gave the price-performance monsters a significant update and launched the literal B version. B2100 – that means smartphone connectivity via Bluetooth connection as well as the integration of Casio’s eco-friendly Tough Solar System. If you’re interested in the new base models: I’ve already tested the squeaky yellow Casio GA-B2100C-9AER and two other sister models a short time ago. Why many people appreciate the affordable entry-level Casio with octagonal homage design so much, I noticed at the latest then. 

Casio G-SHOCK GM-B2100D-1AER
Photo © 2022 by WATCHDAVID® David Drilling – All rights reserved

According to Casio, the iconic as well as angular look is supposed to remind of the DW-5000C, the very first G-SHOCK from 1983. However, a new model gives enough reason to speculate whether the B2100 series might have another role model. 

Casio G-SHOCK GM-B2100D-1AER
Photo © 2022 by WATCHDAVID® David Drilling – All rights reserved

First impression before release

A bit later than the base models, Casio now pushes the full metal version behind, logically now called GM-B2100. So far, the model has only been available abroad. On August 12, i.e. in a few days, the sub-series with three references will also premiere at European retailers as well as in the online store. In black and rosé gold, first videos of YouTubers make a promising impression. However, the enthusiasm among fans is greatest for the G-SHOCK GM-B2100D-1AER. Many want to recognize a Royal Oak in the silver-colored metal watch. At least at a cursory glance, the distinctive octagonal bezel is not visually dissimilar to the classic. The prestige factor alone could make the model a sure-fire winner. 

The biggest difference to the luxury timepiece, however, might be in the price. Instead of several 10000 euros, the three models “only” cost between 549 and 599 euros. Compared to the resin models, that’s still a hefty premium of about 400 euros. Consequently, the task in this watch review is to answer where these are hidden. Exceptional materials and workmanship or just the optical proximity to the Royal Oak? 

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The Casio G-SHOCK GM-B2100D-1AER on the wrist

Casio G-SHOCK GM-B2100D-1AER
Photo © 2022 by WATCHDAVID® David Drilling – All rights reserved

Casio specifies dimensions of 49.8 x 44.4 millimeters. That sounds bigger and scarier than it is. After all, the Casio G-SHOCK GM-B2100D-1AER is not a breaker of men’s watches. On the wrist, the mix of analog and digital watch looks rather medium-sized and elegant, which I personally like. I’m also a fan of the slim build height of just 12.8 millimeters, which is thanks to the eco-friendly drive. If you like it even slimmer, you’ll have to reach for the cheaper GA watches. So, there are differences already. Unsurprisingly, this also applies to the weight. Nevertheless, the Casio G-SHOCK GM-B2100D-1AER weighs 165 grams, which is not as much as you would expect from classic stainless steel watches of this size with automatic movement. The reason for this is once again the lightweight movement. 

A Daily Rocker

In fact, it must be acknowledged without envy that the Casio G-SHOCK GM-B2100D-1AER leaves a lasting impression on the wrist and, from a distance, at least looks similar to a Royal Oak. Thankfully, the watch has enough independent design elements to avoid being dismissed as a dubious copy of the luxury timepiece. The hybrid dial has retained the G-SHOCK design language with its large line indices and diamond-shaped display. 

The Casio G-SHOCK GM-B2100D-1AER is a wristwatch for everyday use. In my opinion, the classic stainless steel look makes it much more timeless than a yellow GA-B2100C-9AER summer watch, where the love fades when you must trade beach volleyball court and swim trunks back in for an office and shirt. A Casio G-SHOCK GM-B2100D-1AER remains an eye-catcher even then. In silver, it is certainly even more so than the two sister models GM-B2100BD-1AER and GM-B2100GD-5AER. The former is probably the most sporty of the three models in all black, while the copper version can be loved or disliked.

A case on a premium level

Photo © 2022 by WATCHDAVID® David Drilling – All rights reserved

The secret star is the case, which is literally more than just metal, even if the designation “full metal” initially suggests it. The bezel and case are made of stainless steel, the workmanship of which is truly outstanding. There is nothing to complain about here. Even more, the watch is reminiscent of the high-priced top models from the Japanese. Matching the bracelet, the case is made of alternating textures that are either highly polished or brushed. Between the case and the bezel, a material is used that I wouldn’t have suspected here, but it makes sense. Fine resin damping elements cushion the pressure of impacts on the module inside the case. Resin is used across the board as case material in the GA-B2100 models. 


Casio claims to have applied elaborate forging, cutting and polishing processes to the bezel and case. This can be seen, among other things, in the circular hairline finish of the bezel. The octagonal DW-5000C (or Royal Oak, for that matter) homage feels good and conveys value. The black and rose gold color of the sister models respectively comes from an IP finish. 

Last but not least, we expect outstanding practicality from a G-SHOCK. As it used to be called: Triple-G – dives up to a water pressure of 10 bar, survives falls from 10 meters and runs for 10 years. The Casio G-SHOCK GM-B2100D-1AER has already proven its shock resistance. Meanwhile, the watch withstands not only a pressure of 10, but 20 bar. Thus, nothing stands in the way of diving excursions. 

The front is adorned with mineral glass. It is scratch-resistant and fulfills its purpose. Nevertheless, the watch lover in me would have liked sapphire crystal, which would have been even more valuable. 

Sustainable thanks to solar power

Photo © 2022 by WATCHDAVID® David Drilling – All rights reserved

After several years of full reliability, even a long-lasting quartz movement eventually breaks down and must be replaced and thrown away. For a few years now, Casio has rethought its concept and incorporated the Tough Solar System. The new 2100 generation now also benefits from this technology. Invisible solar cells sit under the dial. They convert solar energy into electricity, which powers the movement. Excess energy is fed to a rechargeable battery and can be used when needed, so that the functions can be used even if the watch has not been in contact with light for a long time. In my experience, it takes forever for the reserves to be exhausted. I have tested quite a few timepieces with Tough Solar System. Never did it happen that the battery storage was exhausted. 

The dial, its functions and the bracelet

Casio G-SHOCK GM-B2100D-1AER
Photo © 2022 by WATCHDAVID® David Drilling – All rights reserved

A two-layer construction allows for a three-dimensional dial with depth. Its quality of workmanship does not fall in comparison to the case. The dial was manufactured using precision injection molding technology. The dial ring was also steam-coated. In my opinion, the angular, technical-looking design of the indices and hands suits the full metal look best. 

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It is also easy to read, even if the indices were only coated with a weak luminous material. What the heck, in the dark you reach for the Super Illuminator anyway, a bright dual-LED illumination that you activate via the Light pusher. 

Even though the focus of the Casio G-SHOCK GM-B2100D-1AER is on design and materials, it should not go unmentioned that the technical functions are up to date. I had missed it on the Mudmaster last time, here it is indispensable again: the associated app, via which you can intuitively access the most important functions of the Casio G-SHOCK GM-B2100D-1AER. Time, world time, alarms, stop times, a calendar and much more can be set and controlled here. 

Casio G-SHOCK GM-B2100D-1AER
Photo © 2022 by WATCHDAVID® David Drilling – All rights reserved

Finally, the design of the bracelet is strongly reminiscent of the first G-SHOCK. The links are made of stainless steel, but they are very light and can be “pushed out” individually to adjust the bracelet to the appropriate length. Thanks to the folding clasp, it offers a secure hold in everyday life. 

My conclusion about the Casio G-SHOCK GM-B2100D-1AER

The Casio G-SHOCK GM-B2100D-1AER is an unintentional homage to two watches at once. You could even say its design combines the best of DW-5000C and Royal Oak. Within the 2100 series, it is certainly the most timeless. A watch you’ll always enjoy wearing, every day. A real daily rocker. The Casio G-SHOCK GM-B2100D-1AER is also suitable for those who have not been able to get used to the resin look of the other models in the collection and prefer a classic look. The case and bezel are a real pleasure to look at with their workmanship. 

In the end, everyone must answer the question for themselves whether they want to spend four times the base price of an ordinary GA-B2100. Those who can do without stainless steel and the prestige of a Royal Oak should go for these models. All others will love the exclusive character of the full metal G-SHOCK.

More about Casio and the G-SHOCK GM-B2100D-1AER

Here you can find the watch in the store

All Casio watch reviews in my blog

Watch photography


Technical Details

NameCasio G-SHOCK GM-B2100D-1AER

Reference numberGM-B2100D-1AER


Categorydigital watches

Price from549,- euros

Warranty2 years

Case Material316L stainless steel

Diameter49.80 mm x 44.40 mm

High12.80 mm

Watch Glassmineral glas

Watch TypeSolar

Waterproof20 bar (200 m / 660 ft)

Movement NameCasio Tough Solar System

Functions12 hours counter / 24 hours counter / Alarm / Bluetooth Connection / date / GMT / hour / Minute / second / small second / Stop-second



Special Featuresdigital display / hands filled with luminous material

Bezelgrey / stainless steel

Bracelet Colorgrey

Bracelet Material316L stainless steel

Clasp316L stainless steel / folding clasp

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