Casio G-Shock GA-B2100 – Unbiased Review

It seems that Casio wants to continue taking advantage of its Casioak 2100 range: a few days ago they launched the new model with Bluetooth connectivity and solar charging, the GA-B2100, which join the original Casio G-Shock GA-2100 models (resin and without Bluetooth or solar charging) and Casio G-Shock GM-2100 watches (the metal version without Bluetooth or solar charging).

  • It is an analog, digital watch with a striking design (it has an octagonal bezel) and a black dial with a mini digital screen where we can check the date (month and day) and see the seconds. 

We have been testing the yellow version, the Casio G-Shock GA-B2100C-9AJF, but they have also launched other colors with positive or negative screens: GA-B2100-1A1ER (black color, inverted screen), GA-B2100 -1AJF (black color, screen positive), GA-B2100-2AJF (blue color, screen inverted), GA-B2100-3AJF (green color, screen inverted).

Without a doubt, the yellow model is the most striking, and the readability of the screen is very good. Solar charging is a tremendous addition and Bluetooth… well, it depends on your tastes. Many people prefer that they add radio frequency time synchronization. The problem with this model is that Casio uses a new app for smartphones (and it is the fourth active one). We’ll talk more about it later.

What will be the next step for Casio with this G-Shock range? Well, it looks like they released a Casio G-Shock 2100 with Bluetooth, solar charging, and metal. Why haven’t they taken it out directly? Probably so that we keep buying multiple versions of the model until we get to our holy grail… Casio rarely ever offers the full-featured watch. He is taking it out little by little.

We have included this model among the best Casio G-Shock watches.

Page Contents

Casio G-Shock GA-B2100 watch – Opinion and analysis

Casio G-Shock GA-B2100C-9AJF – Features, design, and manufacturing

  • Bluetooth-Smart
  • Smartphone time
  • Super highlighter
  • Shock-resistant solar power system
  • Neon display
  • Universal time function
  • Stopwatch – 1/100 sec. – 24 hours
  • Timers – 1/1 second – 24 hours
  • 5 daily alarms
  • Button sound on/off
  • Needle movement function
  • Phone locator
  • Indication of the day of the week in several languages
  • Automatic calendar
  • 12/24 hour timekeeping
  • Mineral crystal
  • Carbon-reinforced resin shell
  • Resin strap
  • Buckle
  • Water resistance rating (20 bar)
  • Dimensions: 48.6 x 45.4 x 11.9mm
  • Weight: 52 grams

One of the things that Casio fans most demanded with the 2100 models was that they incorporate Tough Solar charging technology, and Casio has finally done it with these models, the Casio G-Shock GA-B2100 (that B is for Bluetooth ). In addition, they have added Bluetooth connectivity to make life easier for us when setting the clock.

But let’s go first for the “unpacking”. The watch comes with a typical G-Shock cardboard box and inside the aluminum can with instructions and a warranty card. We have bought it from a reputable store, so we are sure that it is an original Casio G-Shock and not a fake one.

The watch has the same manufacturing quality as the original model, the strap and case are made of resin, while the inner case is Carbon Core Guard (which improves shock resistance compared to older models).

What is most striking about this particular model is its yellow color, the perfect color, and watch for summer, and Casio knows it very well. In addition, it has mineral glass and a black dial where a few things stand out (it is a digital-analog watch):

  • The positive screen is much more readable than in the other models that we have tested (the original and the metallic one). If you have to buy this model, buy it with a positive screen. You will appreciate it.
  • Very striking and embossed white indexes: they give it a nice touch in contrast to the black dial.
  • White hour and minute hands with a striking gray center. It’s a shame they didn’t have a second hand. They have light.
  • A small dial to the left of the dial displays the functions and modes of the watch with a yellow hand.
  • Just above the digital screen, we find the words Tough Solar in red and Bluetooth in blue. All a success.
  • The rest of the words are found in a faint gray color.

The watch glass is mineral, which we expected at this price level. It is protected by the edge of the box.

If we look at the sides of the watch, we see that the 4 typical Casio buttons are slightly protected by the resin case. If you have big fingers, it will cost you a bit to press them. Right on the edge of the box, we have written what each one is for. If you have used another Casio G-Shock, this one works exactly the same, with the advantage that by being able to connect via Bluetooth to your phone, you can configure the entire watch more easily.

Clock lighting? Well, the truth is that it is quite powerful. We can press the button and it goes directly to the digital screen on the right of the sphere. Both the minute and hour hands have lumen. It’s not as good as a Seiko or Citizen watch, but it gets the job done for part of the night. A pity that the indexes do not have a lumen.

If we now go to the back, we see that it is screwed on with 4 screws and that they indicate a lot of things on it. Mainly the module number, which is Carbon Core Guard, Tough Solar, and water resistance.

But what is most striking is that we have a quick-release strap, something that is always appreciated in these watches. You move the witness a little and you have already removed the strap. Both the buckle and the handle are black.

Strap quality? Typical Casio. It is not our favorite. Something hard, typical of the cheapest Casio. You have to do a bit with it until it molds to your wrist.

You may be interested in other collections of Casio watches:

Casio G-Shock GA-B2100C-9AJF: how it looks on the wrist

It is a watch with a relatively small dial, so it fits very well on all types of wrists. You can check it out with our guide: What size watch should I buy for my wrist? It is a very light watch and you hardly notice that you are wearing it.

Casio G-Shock GA-B2100C-9AJF: Features

The most remarkable thing about the watch is that it has two new functions compared to the Casio G-Shock GM-2100 and the Casio G-Shock GA-2100: It has solar charging and Bluetooth connectivity.

Without a doubt, having a solar charger is the most important thing. Here are Casio’s directions for charging:

Light level (lux)Approximate charging time

  • 50,000 8 minutes
  • 10,000 30 minutes
  • 5,000 48 minutes
  • 500 8 hours

Sunny day, outdoor (50,000 lux)

  • Battery depleted -> Medium load 3 hours
  • Medium load -> High load 24 hours
  • High Charge -> Full Charge 7 hours

To check the charge level just go to the small dial on the left of the dial: In the Timekeeping Mode, the charge level is indicated by the mode hand (H – High charge; M – Medium charge; L – Low stack). If the digital screen goes blank, you don’t have any battery. If an R appears on the screen, it means that the watch is using a lot of battery. If the battery is exhausted and you turn on the clock light and [CHG] appears, it is charging correctly.

As for Bluetooth connectivity, you first have to download the Casio app for this watch… How? Isn’t it the same as for other models? Well no. We already have the G-Shock Connected app, G-Shock Move, Edifice Connected, and Casio Watches installed on an iPhone.

  • In this case, you need the new Casio Watches app (iOSAndroid ). It looks like this is Casio’s 19th attempt at making a good app for its watches.

In this case, the first thing you find when you install it is a screen with news from Casio and its new watches, then you can link the compatible watches by signing up on the Casio website. It seems that Casio has not learned anything from Garmin and its excellent applications for its sports watches.

If we proceed to use the app, register with Casio to be able to link the watch, and it will automatically appear in the “My Watch” section. To connect the clock you have to press the lower button on the left for a few seconds. The process is simple if you already have a Casio account created.

You have to choose the model, enter the module number and confirm all the data that appears on the screen.

When you enter the clock section in the app, it tells you the battery charge, you have a link to the manual and then a large number of menus where you can change all the clock settings:

  • Alarms
  • Timer
  • Reminder
  • World time and your country
  • Bluetooth time synchronization
  • Manual hand adjustment
  • Find phone
  • Clock settings: sound, keys, light, display, energy-saving…
  • Tutorial

In this sense, everything becomes easier by doing everything from the app instead of the old keystrokes on the clock itself (but you can do it the traditional way).

  • You have to send the updates to the clock by pressing the button at the bottom so that they are changed correctly.

The functions of this watch are simple: timers, 5 daily alarms, a stopwatch… and Bluetooth adds the location of the phone.

You can also change the language of the days of the week and adjust the time to 29 different time zones.

The Casio G-Shock GA-B2100C-9AJF is probably not the toughest G-Shock watch in the entire range, but it more than delivers.

If you want a tougher watch, go for the Casio G-Shock GWR-B1000 Gravitymaster (or CASIO GWG-2000- G-Shock Carbon MUDMASTER Radio Solar Triple Sensor) or the Casio G-Shock GW-9400 Rangeman.

Conclusion: Is it worth buying the Casio G-Shock GA-B2100?

It’s a big upgrade from the 2100 range. We finally have solar charging (and Bluetooth). The design remains striking, it has become a modern classic, with a timeless design like the Casio G-Shock GW-M5610 or the Casio G-Shock GW-5000.

In yellow it is very striking, it has a small face, perfect for small wrists, and it is a very light watch. The dial has good legibility, and the positive screen as well.

Right now, Casio is missing only one thing with this model: that it be metallic, but it will probably be one of its next releases.

Is Bluetooth worth it? It makes it very easy for us to configure the watch settings and saves us from having to configure it directly on the watch. The time synchronization is done by Bluetooth (it does not have a radio frequency). The drawback that can be put is that we have to use a new app on our phone… and Casio already has a few (it is somewhat confusing to know which one you have to use)…

In favor:

  • Timeless and very striking Casioak design
  • Yellow color
  • Highly readable positive display
  • Good dial design
  • With Carbon Core Guard
  • With solar charge
  • With Bluetooth
  • Light and with a small sphere
  • Good price


  • No radio frequency time synchronization
  • The box is not metal
  • Somewhat stiff strap
  • Without seconds hand
  • No lumen in indices (somewhat weak lumen in hands)
  • Why does Casio have so many different apps for each watch model?
Check it on amazon

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