G-Shock debuted a premium metal-covered version of its contemporary 2100 series in 2021, followed by an even more upscale full-metal variation in 2022.

Casio’s G-Shock 2100 series all share octagonal-shaped bezels — are available in resin, translucent resin, metal-covered, and full-metal cases —  and are nicknamed “CasiOak” because of a resemblance to the famed Royal Oak. The new 2022 G-Shock GMB2100D-1A Full Metal represents the first luxe metallic version of Casio’s bestselling 2100 series. The GMB2100 series starts at $550 and is available in three 44.4 mm stainless steel references — silver (GMB2100D), all-black IP (GMB2100BD), and rose gold IP (GMB2100GD).

G-Shock GM2100 next to GMB2100

Full-Metal Upgrades

The Full-Metal GMB2100 received a number of upgrades over the Metal-Covered GM2100 (we reviewed the metal-covered GM2100 series in 2021). First, the case construction is more complex and robust and uses a screw-in caseback and integrated bracelet. Second, the dial has a more complicated multi-layered design and features a luxurious embossed (raised) G-Shock logo compared to a printed (flat) logo on the Metal-Covered version. Third, the Full-Metal dial adds lume on all twelve-hour markers, not just the hour and minute hands, as seen on the Metal-Covered model, which greatly enhances legibility. Last, the new GMB2100 adds precision Bluetooth time syncing, via the Casio Watches app, and automatic solar-powered recharging.

G-Shock GMB2100D-1A Full Metal CasiOak laying on side

The Case

Both the cases of the GM2100 and GMB2100 measure the exact same 44.4 mm in diameter, however, the GMB2100’s additional Bluetooth and solar functionality require a new movement module, a new dial structure, and a construction that results in the full-metal case being half a millimeter taller (49.3 mm vs 49.8 mm lug-to-lug) and a millimeter thicker (11.8 mm vs 12.8 mm thickness).

Despite the subtle one-millimeter of difference in thickness, you do notice the less expensive metal-covered model feels slightly thinner on the wrist, perhaps because of how the strap and caseback let the watch sit on your wrist compared to the bracelet. Either way, both watches are the exact same diameter and within a millimeter of one another, or less, on the other specifications, so there’s not a vast difference between the two as far as wrist presence.

G-Shock GM2100 and GMB2100 exploded views
G-Shock GM2100 and GMB2100 exploded 

As you can see in the exploded graphics the metal-covered construction requires fewer components and is arguably less sophisticated. The GM2100 series has a forged metal cover, with a glass-fiber reinforced resin case, and a resin strap — whereas the Full Metal GMB2100 has a full metal case with fine resin inner cushioning, a DLC-coated screw-in caseback, a 3-prong bracelet attachment structure, and a stainless steel integrated bracelet.

That said both models have excellent shock resistance, a depth rating of 200 meters, and a similar feel for the pushers so while the full-metal is superior to the metal-covered, you’re not losing durability per se by going with the less expensive model. It’s more accurate to say that the new structure is stronger though either is designed to stand up to serious shock and can be worn in harsh environments.

G-Shock GM2100 vs GMB2100
G-Shock GM2100 vs GMB2100

Furthermore, both models have a flat mineral crystal that’s sunken below the plane of the bezel, meaning neither is likely to scratch.

As far as the strap versus the bracelet, the Metal-Covered GM2100’s resin strap fits well and is comfortable, although it has a stiff rather than soft feel, and it’s connected to the case via traditional spring bars and has levers that slide on each side so you can switch the strap without any tools. Whereas the Full Metal GMB2100 has screw bars, which are stronger, and allow the bracelet to be removed with a watchmaker’s flat-head screwdriver. The bracelet links, however, have push-pins, not screw-pins, which require you to push them out versus requiring a screwdriver. The bracelet features a dimpled design borrowed from the original look of the 1983 DW-5000C, and has a premium look and feel, and with removable links and 4 micro adjustments on the push-button claps, the fit can be customized more precisely than a strap. Depending on your preference, the total weight of the Full Metal GMB2100 is 168.9 grams versus 71.5 grams for the Metal-Covered GM2100 model.

G-Shock GMB2100D-1A Full Metal CasiOak laying portrait

The Dial

With a dual-layer construction, the GMB2100 dial is more luxurious and is designed to accommodate the transmission of sunlight/artificial light through the dial, which recharges the long-lasting internal battery. Casio lengthened the hour markers, raised them, and added texture, all of which enhances the look. Accentuating the dial further is a shiny raised (embossed) G-Shock logo, at 12 o’clock, as opposed to the flat (printed) G-Shock logo seen on the dial of the GM2100.

Overall, the new GMB2100 dial is another level above the GM2100, however, the solar-powered recharging system necessitates a translucent material and thus prevents the application of a brushed or sunburst finish on the dial, whereas the GM2100 does feature a nice vertical brushed treatment. Also, the higher-end GMB2100 comes with a monotone color scheme, which looks menacing but is perhaps not as legible as the silver dial seen on the GM2100.

G-Shock GMB2100D-1A Full Metal CasiOak lumeshot

One simple yet useful upgrade Casio made to the GMB2100, is the addition of lume for the hour markers, not just luminous hour and minute hands, as was the case with the GM2100. Both have on-demand dual LEDs for visibility in total darkness, still, the fully-lumed dial is a nice touch.

A mixture of vapor deposition and grind mark finishing on the outer ring and indices, respectively, adds a luxurious texture to the dial.

On The Wrist

The GMB2100 wears great on the wrist thanks to the relatively conservative 44.4 mm diameter and 49.8 mm lug-to-lug by 12.8 mm case size. Being that this has an aesthetic resemblance to the Royal Oak, going much larger would put it into a whole other territory. And on that note, I think that if this watch reaches critical mass for Casio, it would make sense to offer it in a smaller size as well, just as they have with previous resin, translucent resin, and metal-covered models.

G-Shock GMB2100D-1A Full Metal CasiOak wristshot

The metal bracelet of the GMB2100 is nicely tapered and feels good on the wrist. Yet what’s practically unavoidable for any watch with an integrated metal bracelet, is the added heft. The bracelet, and to a lesser extent, the heavier module and full-metal case construction, make for a watch that weighs 168.9 grams versus just 71.5 grams for the GM2100 with a resin strap. Titanium, forged, and ceramic are three options to reduce weight from bracelets, however, those also add cost. A fourth option, and one that’s been used by Casio in the past, is to essentially hollow out a  steel bracelet and fill it with resin, which significantly reduces weight while not exceedingly raising the cost. Two examples of that within that MT-G collection can be seen here and here. Despite weight savings, some consumers will never want a strap over a metal bracelet, especially for a sports watch. Maybe because of the looks, or perhaps they prefer the heavier feel or both. Nevertheless, Casio offers both, although, for the time being, there’s no way to add a factory metal bracelet to the GM2100 or a factory strap to the GMB2100.

G-Shock GMB2100D-1A Full Metal CasiOak double LED

The Features

Beyond the core features, such as high shock resistance, 200 meters of water resistance, Japanese quartz accuracy, Bluetooth time syncing, and solar power, the GMB2100 has a plethora of functions and benefits.

The high-brightness double LED light can be set to illuminate the dial for 1.5 or 3 seconds, at the push of a button, and includes afterglow. This is the same for both the GMB2100 and the GM2100.

When connected (paired) to the Casio Watches App via the wireless Bluetooth mobile link technology which is only available on the higher-end GMB2100, not the GM2100, the watch sets itself and calibrates the time using the internet time server up to 4 times per day — for incredible precision.

With the Casio Watches App, you can set the world time with 38 time zones (38 cities + coordinated universal time), city name display, daylight saving on/off, auto summer time (DST) switching, and Home city/World time city swapping (approximately 300 cities in total).

Pressing a button on the watch records the date, time, and position on a map, which is then viewable within the Casio Watches App. The watch can remind you of up to five upcoming events, which you set within the app. There’s a phone finder function activated from the watch.

The built-in stopwatch is accurate to 1/100th of a second for the first 60 minutes, after which the accuracy changes to one second, and the total measuring capacity of 24 hours. You can measure elapsed time and lap/split time and there’s also a 60-minute countdown timer.

There are 5 daily alarms available to set and an on/off hourly time signal, as well as a battery level indicator so you can ensure that the battery has received enough sunlight/artificial light. To conserve energy, the Power Saving features blanks out the display automatically when not in use (left in the dark).

A full auto-calender displays the day (days of the week can be selected in six languages), date, month, and year (accurate to 2099). You can run the digital display in a 12/24 hour format. The push buttons can be set to have a tone when operated or not.

The hour and minute hands move like normal quartz-powered analog hands, with the exception that the minute hands move every 20 seconds, to conserve energy. The dedicated analog display on the right shows the battery level and mode. The small digital display can show hours, minutes, seconds, AM/PM, month, date, and day. Hand shift feature which allows you to move the analog hands out of the way to provide an unobstructed view of the digital display.

Even with a mobile Bluetooth connection, the movement is accurate to -/+ 15 seconds per month. The approximate battery operating time is 7 months when fully charged, with normal use, even without light exposure, and 18 months when stored in total darkness and the power save mode activated.

G-Shock GMB2100D-1A Full Metal CasiOak caseback


If you want the most advanced, upscale 2100 Series “CasiOak” model, the GMB2100 is it. It comes at a steep price, starting at $550 (as shown), but for that price, you get the octagonal bezel aesthetic coupled with all the latest technology including solar recharging, precision Bluetooth timekeeping, and a robust full-metal case and bracelet.

For those of you who don’t need Bluetooth time syncing or solar charging, or perhaps want to disconnect from devices — the new GMB2100 underscores how good of a deal the GM2100, which starts at $200, actually is.

Of the DW-5000C-derived Casio designs, this is one of the best, and while I’d like to see a little more contrast on the dial of the Full Metal GMB2100 or an option for a strap, both the Metal-Covered GM2100 and the Full Metal GMB2100, represent great looking watches, with good Japanese quartz precision, and incredible durability.

Learn more at Casio.




G-Shock CasiOak GMB2100 Full Metal

Reference: GMB2100D-1A

Year: 2022

Total Weight: 168.9 grams

Case Diameter: 44.4 mm

Case Thickness: 12.8 mm

Lug-to-lug: 49.8 mm

Crown Diameter: No crown

Glass: Mineral crystal

Movement: Module 5691

Depth Rating: 200 meters

Bracelet: 23 mm/13 mm

Posted by:Jason Pitsch

Jason is the founder of Professional Watches and specializes in writing, product photography, and digital marketing.