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Casio G-SHOCK GA-2100K-2AER Smokey Blue Resin Strap Watch - W17589
Ref. GA-2100K-2AER
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Stepping up in the same dial colour
The GA-2100 arrived in 2019 drawing on the angular language of the DW-5000C and AW-500, and the octagonal case that earned it the CasiOak nickname has since become one of the more recognisable shapes in the G-SHOCK lineup. This Smokey Blue release belongs to the Smoked Lights sub-series launched in 2026, built around the visual grammar of electronic music venues — laser strobes, stage haze, neon cutting through dark rooms. The piano-black dial surface and neon orange hand accents carry that reference without leaning on it too heavily. What makes the GA-2100 worth attention is the Carbon Core Guard construction, which holds the case to 11.8mm despite a 200m rating — genuinely unusual geometry for a watch built to those standards, and the reason it disappears under a cuff in a way that most G-Shocks simply do not. At 51 grams the fit is light enough that the 45.4mm footprint rarely asserts itself. The translucent smoky blue strap runs integrated into the case and adjusts across a wide enough range to suit most wrists without fuss.
- Reference
- GA-2100K-2AER
- Brand
- Casio
- Collection
- G-Shock
- Case size
- 45.4mm
- Case thickness
- 11.8mm
- Lug width
- 16mm
- Case material
- Resin
- Case shape
- Octagonal
- Dial
- Black
- Crystal
- Mineral
- Movement
- Quartz
- Functions
- Stopwatch, Countdown timer, Alarm, Backlight, World time, Perpetual calendar, Dual display, Digital display
- Water resistance
- 200m
- Bracelet / strap
- Rubber strap
- Strap colour
- Blue
- Clasp
- Buckle
- Lume
- Luminous
- Retailer
- F.Hinds
Additional specifications
- Lug-to-lug
- 48.5mm
- Warranty
- 2 years
Learn more about Casio
Tadao Kashio founded Kashio Seisakujo in Tokyo in 1946 as a machine shop. The company's first success was a finger ring that held a cigarette, and its second was the 14-A of 1957 — the world's first all-electric compact calculator, which used solenoids rather than gears.
Casio entered watchmaking in 1974 with the Casiotron, a digital watch with an automatic calendar that knew the varying lengths of months. The company approached watches as an electronics manufacturer rather than a horological one, and that difference produced the G-Shock.
The G-Shock came from a single engineer, Kikuo Ibe, who broke a watch his father had given him and set out to build one that could not break. The specification was three tens: survive a ten-metre drop, ten bars of water pressure, and ten years of battery life. It took over two hundred prototypes, and the solution was suspending the module inside the case on a cushioned internal structure rather than mounting it rigidly. The DW-5000C shipped in 1983.
It became one of the most durable product designs in any category, adopted by militaries, emergency services, and skateboarders alike, and Casio has since added solar charging, radio and GPS timekeeping, Bluetooth, and full-metal and carbon variants.
Casio also produces the Edifice, Pro Trek, and Oceanus lines, and remains an independent Japanese public company.
- 1946
- Tadao Kashio founds the company in Tokyo.
- 1974
- The Casiotron is Casio's first digital watch.
- 1983
- The G-Shock DW-5000C survives Kikuo Ibe's three-tens brief.
- 1994
- The Frogman extends G-Shock to ISO dive certification.
Manufacturer’s guarantee
What the specifications mean
A watch built to be worn hard and got wet.
Strengths
- 200m water resistance, rated for actual diving
- 48.5mm lug-to-lug keeps the 45.4mm case wearable
- Luminous hands and markers for low light
- Second time zone for travelling
- Sits in the lower half of Casio's range as we list it
Worth knowing
- 45.4mm is a large watch with real presence
Compare alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | GA-2100K-2AER |  W1049G6 |  1792233 |
|---|---|---|---|
| Price | £109 | £119 | £109 |
| Case size | 45.4mm | 45mm | 44mm |
| Water resistance | 200m | 100m | 100m |
| Movement | Quartz | Quartz | Quartz |
| Strap | Rubber strap | Silicone strap | Silicone strap |
| This watch |
|
|
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 200m it is rated for swimming, snorkelling and recreational diving.
Will the glass scratch?
It can, over time. Mineral glass handles daily wear but will pick up fine scratches that sapphire would not.
Does it need a battery?
Yes. It is quartz, so expect a battery change every two to three years at a jeweller.
What size strap does it take?
16mm. Any strap of that width will fit, and on most modern watches quick-release bars make the swap a two-minute job with no tools.
Will it fit my wrist?
Lug-to-lug is 48.5mm, which suits wrists from roughly 16.5cm (6½ inches) upward.
Lug-to-lug decides fit more than case diameter does.
Is it a men's or women's watch?
Listed as unisex, and at this size it suits any wrist that takes the dimensions.
Cheapest place to buy
F.Hinds is the only UK retailer we track stocking this reference, so there is nothing to compare it against today.
Who are F.Hinds?
F.Hinds has been run by the same family since 1856 and is now in its fifth generation, with more than 115 shops across England and Wales. They are a member of the Responsible Jewellery Council and an Authorised Diamond Dealer.
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