G-Shock Carbon Core Guard by Casio – Watchmaker Review

Bumping Into The G-Shock Carbon Core Guard

Like a lot of good things in life this review of a Casio G-Shock Carbon Core Guard Watch was the result of an opportunity seized rather than outcome of any careful planning.  It all started on a recent trip to London during which my daughter announced an urgent need for Puma training shoes which could apparently be best procured from the Puma store on Carnaby Street.  When we arrived there I was delighted to see that right next door was a bright little shop which, as made clear to all the world from the sign above its very clean window, was dedicated to the sale of Casio G-Shock watches.  My daughter and her mum when off to peruse the offerings by Puma and I scuttled into the Casio G-Shock shop like a kid into a sweet shop.

Now quartz watches are not normally my thing and the watches that were lit up around the store were all pretty funky quartz watches and thus quite different to my area of specialization which is mechanical watches (particularly automatic wristwatches and vintage pocket watches).

Casio G-Shock Carbon Core Guard – Watchmaker Review : The Video

I decided, for the record (and for my YouTube channel), to make a video of this work and much of what is contained within this article you can also see in detail by watching this.

Reference of Watch under Test

The exact model of the watch tested in this review was …


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You can checkout the latest price of this watch at both my UK Amazon Store and my US Amazon Store 

The Review Method

As always for this to be a genuinely helpful review I was determined that it should be as scientific and dispassionate as possible.  The plan I came up with was a simple one.  Firstly, as soon as I took it out of the box, I would test the watch’s waterproofing to 50 meters in the pressure testing tank.  After that I would do a detailed inspection of the watch. Finally using the information gathered and in knowledge of the attractive price tag I would judge its value  for money.

I used my normal scoring system with the following criteria which were to be scored as follows.

Scoring system

The watch would judged in three main categories, both scored from 0 to 10

  • Build Quality (Engineering Standard – Reasonably Objective)
  • Looks (Aesthetics – Not quite so Objective!)
  • Value for Money – (dependent completely on the findings of the first two categories)

Strengths and Weaknesses

I also do a quick run through what I see as the strengths and weaknesses of the watch

Build Quality

The build quality was further broken down into the following areas .

  • Movement
  • Dial Design
  • Case
  • Strap
  • Features
  • Water Resistance
  • Crystal

Movement:  It’s a quartz movement so we know it is accurate to +or- 15 seconds a month so this is more a look at the refinement and quality of the movement.  This section also includes the Keyless works.

Case:  It’s billed as a super rugged case with a Carbon Core Guard … ing the movement.  I take the watch apart to look at the implementation of this.

Strap:  A simple assessment of the comfort and resilience of the strap.

Features:  This watch has a lot of features so I look at these seems pretty important.

Water Resistance:  My kit tests down to a max of 60 meters water pressure so and in this assessment I tested the water resistance down to 50 meters,

Crystal:  A simple assessment of the crystal installed

Lume:  There is no lume!  But there is a natty LED dial light so this section deals with the effectiveness of this alternative lighting method.

Review Findings Detail

It’s fair to say that right this watch took my eye in the shop.  I liked its funky look and the layout of the analogue dial and how this was complemented by the arrangement of the movements digital readouts.

Water Resistance

The first thing I did with this watch was pop it in the pressure testing tank and pump up the air pressure outside the watch to 50 meters worth of water pressure.  Anything wrong with the waterproofing and this pressured air would have found its way inside the Carbon Core Guard and into the movement and behind the crystal.  Then I dunked the watch into the water and slowly released the pressure in the tank.  If air had got inside the case the differential in pressures would now cause a rush of air from the watch case into the surrounding water.

If you watch the video (the pressure test starts 123 seconds into it) you will see that some bubbles were seen emerging from the watch when the air is released from the tank but these are exclusively from the pusher cavities and we should expect some air to have been trapped in there under pressure so that is fine.  But the Carbon Core Guard and its bespoke gasket top and bottom held firm.  No steady stream of bubbles or significant rush of air was witness.  the watch was watertight to 50 meters

But the Carbon Core Guard and its bespoke gasket top and bottom held firm.  No steady stream of bubbles or significant rush of air was witness.  The watch was watertight to 50 meters

Water Resistance Score:  10 out of 10

Movement – Casio 5590 Module

The movement inside this Casio G-shock Carbon Core Guard watch is the Casio 5590 module.  This is a chunky big quartz movement containing zero jewels.  This movement ensures it is supplied with plenty of power as not one but two batteries are required.

In supplying so many features and the complicated mix of analogue and digital displays its difficult not to be impressed by this movement.  The absence of jewels is a concern but this is an economy level quartz watch so I guess finding jewels in the movement would have been a surprise anyway.

Having used the watch an tested the five main function areas it was apparent that this movement should score highly as it performs extremely well when being asked to do a lot of things.  The lack of any jewels dragged the score down to a very respectable 8 out of 10.

The user instructions for this module can be downloaded from the casio support page for the 5590

Movement Score:  8 out of 10

Dial Design

I like the dial design of this watch.  In the video I explain its provenance and the way in which the guys at G-Shock have placed the various parts of the dial in a sensible way and in a manner that gives a nod to previous designs.  The seconds digital display is at the 6 o’clock position which is where you would find the minute subdial on a pocket watch.  The date in time mode is at the three o’clock position which is the most common place for a date window on a dial.   The design is well thought through.

There are two things about the detailed implementation of the dial that I did have concerns over.

  • The black counter balance on the minute hand masks the the hour hand when the hands are 180 degrees apart.
  • The digital displays need the watch to be tilted into the correct light to get a clear view.  When this is done it the displays are very clear but you cannot simply glance down and always see the information without also tilting the watch into the light.

Dial Design Score:  8 out of 10

The Case

The case is particularly important in this watch as Casio have staked a lot on the Carbon Core Guard concept with this line of watches.  Dismantling the case took no special tools and the design is simple and effective.  The resin case back is very comfortable and the knurled pushers nice and chunky.

The image above shows the carbon core referred to watch’s title.  In addition to this solid ring of carbon around the movement the watch is also blessed with nice big knurled pushers.

image of g-shock pusher
Nice big knurled pushers (under which some air got trapped .. no big deal)

Overall the case was seen to be very robust and nicely designed for resilience and good ergonomics.  I scored it 9 out of 10.

Case Score:  9 out of 10 


As we would expect from an ana-digi piece from the Casio stable the features on this watch far exceed anything you will normally find in high end watches or any mechanical watch.  That which is achievable with software and stepper motors is just so much bigger than can be implemented with wheels, pinions and levers, however cleverly conceived.  The watch has five main modes …

  • Time
  • World Time
  • Stop Watch
  • Alarm
  • Countdown Timer

Cycling around the modes is done via a simple single push of the mode pusher and the mode wheel at 9 o’clock rotates gracefully to indicate which mode the watch is working in.


This is the default mode for the watch as indicated by the bright yellow bar on the mode wheel.  This mode again by default the time will appear in digital format at the 9 o’clock position.   By pressing the start button you can cycle this display through time – date – and day of the week.

World Time

This feature allows you to scroll through ??? world cities and select a city to see the current time in that city.  Once set you can rapidly swap the readout both analogue and digital whilst in the Time mode by pressing and holding the Reset button for a few seconds until you see the word SWAP flashing at the 9 o’clock readout.

Stop Watch

The stop watch mode is pretty clever.  If you have the need to record two separate times for two things that start at the same time but finish at different times, a not uncommon scenario, then the stop watch feature on this Casio G-Shock Carbon Core Guard watch will be able to do this for you.  It takes a bit of practice to get the sequence of pressing the START and RESET in the correct order but I figure if this was something you needed to do you would learn this very quickly and this function would be really very useful.  It does of course also act as a simple START – STOP – RESET stopwatch.  The readout is in hours: minutes:seconds  (at the 9 o’clock position) and 100ths of a second at the 6 o’clock circular display.

Countdown Timer

Somehow the typical lover of G-Shock watches doesn’t also seem to fit the profile of a prolific baker of cakes.  This is a shame as the watch has a handy countdown timer perfect for timing those souffles to perfection.  It’s easy to operate and so long as the you don’t have the radio on too loud in the kitchen you stand a pretty good chance of hearing the alert when the timer has finished counting down.


You can set up o five alarms a day and toggle what Casio term the  ‘signal’ on and off.  Setting an alarm is pretty simple and I guess five a day should be plenty for most peoples needs.  So again this is pretty useful function within the limitations I mention below on loudness of the alarm and the fact that without a light source external to the watch it is pretty much impossible to set the alarm in darkness ( see notes on limitation of the LED illumination ).

Note: The bleep alert for both the countdown time and the alarm is a little quiet.  So long as there is no background noise it will do its job admirably but I fear in a more challenging acoustic environment the noise level my struggle to be heard of the ambient noise.

Features Summary

Without the array of features packed into the g-shock watch by Casio it would be simply a nice implementation of a ana-digi watch.  It’s arguably these features, common as they are in the digital watch arena, that really lift this watch out of the ordinary when comparing as we should against all watches in this price bracket.  The fact is Casio has had a bunch of experience in delivering neat features like the ones accessible via the five modes in this watch and they have done it really when in this instance.  If all the features had been able to be set with the dial light on then this would have scored a 9 or 1o out of ten.  But without that being available I have to cut the score back to a solid 8 out of ten.

Features Score: 8 out of Ten

Scoring Summary

So, with the analysis and testing complete let’s take a look at how this G-Shock watch performed.

  • Movement    – 8
  • Dial Design  – 8
  • Case – 9
  • Strap – 7
  • Features – 8
  • Water Resistance – 10
  • Crystal – 7

Total Score for Engineering and Build Quality:   8.1 out of 10

Aesthetics – The Look of the Watch

The thing about all the G-Shock range and particularly funky black and yellow models like this that theses watch look good so long as you wear them in the correct context.  The context in question is that these watches only really go well with casual and sports clothing.  Casio marketing realises that most people dress casually most of the time so this is not too much of a worry.

So for looks within its intended context this watch scores pretty highly but less so when it comes top versatility.

Weighing up the good looks it has for casual wear and the limitations it has on versatility I have decided to score the watch 7 out of 10 for looks.

Aesthetics Score: 7 out of 10

Value for Money

I paid £119 for this watch at full retail from the Casio G-Shock store on Carnaby Street in London.  This is I think a fair price for this exceptionally robust watch, with 200m water resistance and a whole bunch of potentially useful features.

If the LED dial illume had been able to stay on whilst other functions are being used or set  I think this watch would have scored 10 out of ten for Value for Money.  As it is the ability to use and manage these functions only daylight does detract for the watches overall performance as a funky wrist tool.

I have hence docked 1.0 points of a perfect score and given a score of 9.0 out of ten which of course is still a very impressive performance.

Value for Money Score:  9 out of 10

Final Results and Summary

This G-Shock Carbon Core Guard is a very impressive new offering from Casio.  The Dial Design is great, it looks cool and can be confidently worn with any type of casual or sports outfit.  It has a bunch of useful features and the only real drawbacks are that these features cannot be configured in darkness and the alarm (at least on the piece that I had under test) is maybe a little too quiet.  The watch is rugged, resilient and can be worn swimming or snorkeling without any issues.

Final Results then are

Engineering and Build Quality:    8.1

Aesthetics (Looks):                            7.0

Value for Money:                                 9.0

Final Score:                    8.1

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The Casio Carbon Core Guard watch is available from amazon ….

GA 2000 1A9ER GA 2000 2AJF – Japan Import

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