Casio G-Shock GA-B2100 CasiOak vs Rolex Datejust 41
Casio's diver meets Rolex's dress watch
Quick Verdict
The Casio G-Shock GA-B2100 CasiOak ($100–$150) offers Casio Quartz (Solar-Powered) precision in the tier below the Rolex Datejust 41 ($5,000–$10,000). The G-Shock GA-B2100 CasiOak measures 45.4mm (48.5mm lug-to-lug, 11.9mm thick) and is rated 200m (20 ATM). The Datejust 41 counters with Swiss Made craftsmanship and 100m (10 ATM) water resistance. Both are exceptional watches for their respective tiers.
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Specifications Compared
| Feature | Casio G-Shock GA-B2100 CasiOak | Rolex Datejust 41 |
|---|---|---|
| Price | $100–$150 | $5,000–$10,000 |
| Case Size | 45.4mm (48.5mm lug-to-lug, 11.9mm thick) | 41mm |
| Movement | Quartz Module 5689 (Tough Solar + Bluetooth) | Automatic Caliber 3235 |
| Caliber Type | Casio Quartz (Solar-Powered) | Rolex In-House Automatic, Superlative Chronometer (-2/+2 sec/day) |
| Power Reserve | About 7 months on a full charge without light; about 18 months in power-saving (Casio) | 70 Hours |
| Water Resistance | 200m (20 ATM) | 100m (10 ATM) |
| Crystal | Mineral Glass | Sapphire Crystal with Cyclops |
| Case Material | Carbon Core Guard Resin | Oystersteel |
| Origin | Made in Japan | Swiss Made |
Category-by-Category Analysis
Design & Aesthetics
Casio's design language vs Rolex's approach
The Casio G-Shock GA-B2100 CasiOak features a Carbon Core Guard Resin case at 45.4mm (48.5mm lug-to-lug, 11.9mm thick) with Mineral Glass protection. The Rolex Datejust 41 offers Oystersteel construction at 41mm with Sapphire Crystal with Cyclops. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Quartz Module 5689 (Tough Solar + Bluetooth) vs Automatic Caliber 3235
The G-Shock GA-B2100 CasiOak runs the Quartz Module 5689 (Tough Solar + Bluetooth) (Casio Quartz (Solar-Powered), About 7 months on a full charge without light; about 18 months in power-saving (Casio) power reserve) at standard frequency. The Datejust 41 uses the Automatic Caliber 3235 (Rolex In-House Automatic, Superlative Chronometer (-2/+2 sec/day), 70 Hours reserve) at standard. The Datejust 41 offers a longer power reserve.
Wearability & Fit
45.4mm (48.5mm lug-to-lug, 11.9mm thick) vs 41mm — different wrist presence
At 45.4mm (48.5mm lug-to-lug, 11.9mm thick), the G-Shock GA-B2100 CasiOak has a bolder wrist presence compared to the Datejust 41 at 41mm. Water resistance differs: 200m (20 ATM) vs 100m (10 ATM).
Value & Cost of Ownership
Casio sits in the lower tier
The Casio G-Shock GA-B2100 CasiOak sits at $100–$150 and the Rolex Datejust 41 at $5,000–$10,000. On the specs that outlast any price: the G-Shock GA-B2100 CasiOak uses Mineral Glass with About 7 months on a full charge without light; about 18 months in power-saving (Casio), against Sapphire Crystal with Cyclops and 70 Hours on the Datejust 41. Service intervals are typically 5-7 years for both.
Water Resistance
200m (20 ATM) vs 100m (10 ATM)
The G-Shock GA-B2100 CasiOak is rated to 200m (20 ATM) while the Datejust 41 handles 100m (10 ATM). The G-Shock GA-B2100 CasiOak is better suited for water activities.
Our Verdict
Casio
G-Shock GA-B2100 CasiOak
Choose the Casio G-Shock GA-B2100 CasiOak if you prioritize Casio Quartz (Solar-Powered) engineering, Made in Japan craftsmanship, and 200m (20 ATM) water resistance. At $100–$150, it delivers Quartz Module 5689 (Tough Solar + Bluetooth) with About 7 months on a full charge without light; about 18 months in power-saving (Casio) power reserve.
Check Price on AmazonRolex
Datejust 41
Choose the Rolex Datejust 41 if you value Rolex In-House Automatic, Superlative Chronometer (-2/+2 sec/day) technology, Swiss Made heritage, and 41mm proportions. At $5,000–$10,000, the Automatic Caliber 3235 with 70 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Casio G-Shock GA-B2100 CasiOak and Rolex Datejust 41 represent two distinct approaches to fine watchmaking — the Casio bringing Made in Japan tradition while Rolex delivers Swiss Made engineering.
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Our comparisons are generated from a hand-maintained specification database and reviewed under our editorial standards. We use AI tools to assemble pages from that data. We don’t invent specs: every number traces back to the database, and when we correct an entry, the fix is applied site-wide. As an Amazon Associate, The Horologist earns from qualifying purchases.