The Casio “CasiOak” is the affectionate nickname for the Casio G-Shock GA-2100 series. Casio markets it around its octagonal bezel, but the watch world latched onto the resemblance between that shape and the Audemars Piguet Royal Oak, and the name stuck. It has become one of the most popular G-Shocks ever made, partly because it pairs that high-end silhouette with G-Shock toughness at a budget-friendly price.
Below we go through what makes the CasiOak special and the many colourways it has been released in. If Casio history is anything to go by, the GA-2100 family will keep growing with new special editions for years to come.
Why the CasiOak became a hit
The GA-2100 hit a sweet spot that few watches manage. It is genuinely thin for a G-Shock thanks to Casio’s Carbon Core Guard construction, which uses a carbon-fibre-reinforced resin case to keep things slim and light while still shrugging off knocks. The octagonal bezel gives it an upmarket, almost luxury-sport look, and the analogue-digital display keeps it practical for everyday wear.
Add the usual G-Shock toolkit, 200 metres of water resistance, shock resistance, a stopwatch, countdown timer, world time, and multiple alarms, and you have a watch that punches well above its price.
The colour range
Part of the fun of the CasiOak is choosing a colour. The series launched with restrained tones and quickly expanded into bold and limited-edition finishes. Here are some of the variants that have appeared over the years.
So many references to choose from
Beyond the standard resin-strap models, the GA-2100 has spawned a huge number of spin-offs. A few worth knowing:
- GA-2100 – the original analogue-digital model on a resin strap, the one that started the craze.
- GA-B2100 – adds Bluetooth and Tough Solar charging, so you can sync the time from your phone and never change a battery.
- GM-2100 – the “metal-clad” version with a stainless-steel bezel over the carbon case, the closest the line gets to that luxury-watch feel.
- GM-B2100 – the full-metal interpretation with a steel case and bracelet, plus solar and Bluetooth.
Because the range varies so much and new colours and collaborations appear regularly, it is always worth checking what is currently in stock before you buy.
Should you buy one?
If you want a tough, versatile everyday watch with a design that nods to far more expensive pieces, the CasiOak is hard to beat. It is light, durable, water resistant, and available in enough colours and configurations to suit almost anyone. For many people it ends up being the watch they reach for most, precisely because they are not afraid to actually wear it.
Why is it called the CasiOak?
The nickname combines “Casio” with “Royal Oak”. The GA-2100’s octagonal bezel resembles the Audemars Piguet Royal Oak, so enthusiasts started calling it the CasiOak.
Is the Casio GA-2100 a good watch?
Yes. It offers G-Shock durability, 200 metres of water resistance, a slim carbon-core case, and an upmarket look, all at a low price, which is why it is one of the most popular G-Shocks available.
What is the difference between the GA-2100 and GM-2100?
The GA-2100 has a resin bezel, while the GM-2100 adds a stainless-steel bezel over the carbon case for a more premium, metal look and a slightly heavier feel.
Henrik is our most experienced watch expert and has been in the industry for soon 10 years. He has a good ear to the ground and are following what the big brands do, but also what trends that smalled microbrands and exploring in order to follow whats next in the watch industry.