Casio G-Shock GA-B2100 CasiOak vs Invicta Pro Diver Automatic 23681
Two divers compared — $100–$150 vs $50–$100
Quick Verdict
The Invicta Pro Diver Automatic 23681 ($50–$100) delivers Automatic (Seiko NH35A) technology in the tier below the Casio G-Shock GA-B2100 CasiOak ($100–$150). The Pro Diver Automatic 23681 measures 40mm and is rated 200m. The G-Shock GA-B2100 CasiOak justifies its premium with Made in Japan heritage and Quartz Module 5689 (Tough Solar + Bluetooth). Both represent excellent choices in the diver category.
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Specifications Compared
| Feature | Casio G-Shock GA-B2100 CasiOak | Invicta Pro Diver Automatic 23681 |
|---|---|---|
| Price | $100–$150 | $50–$100 |
| Case Size | 45.4mm (48.5mm lug-to-lug, 11.9mm thick) | 40mm |
| Movement | Quartz Module 5689 (Tough Solar + Bluetooth) | Automatic NH35A |
| Caliber Type | Casio Quartz (Solar-Powered) | Automatic (Seiko NH35A) |
| Power Reserve | About 7 months on a full charge without light; about 18 months in power-saving (Casio) | — |
| Water Resistance | 200m (20 ATM) | 200m |
| Crystal | Mineral Glass | Mineral Glass |
| Case Material | Carbon Core Guard Resin | — |
| Origin | Made in Japan | Invicta (Japanese movement) |
Category-by-Category Analysis
Design & Aesthetics
Casio's design language vs Invicta'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 Invicta Pro Diver Automatic 23681 offers steel construction at 40mm with Mineral Glass. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Quartz Module 5689 (Tough Solar + Bluetooth) vs Automatic NH35A
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 Pro Diver Automatic 23681 uses the Automatic NH35A (Automatic (Seiko NH35A), standard reserve) at standard. The G-Shock GA-B2100 CasiOak edges ahead on power reserve.
Wearability & Fit
45.4mm (48.5mm lug-to-lug, 11.9mm thick) vs 40mm — 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 Pro Diver Automatic 23681 at 40mm. Water resistance differs: 200m (20 ATM) vs 200m.
Value & Cost of Ownership
Invicta sits in the lower tier
The Casio G-Shock GA-B2100 CasiOak sits at $100–$150 and the Invicta Pro Diver Automatic 23681 at $50–$100. 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 Mineral Glass and a standard reserve on the Pro Diver Automatic 23681. Service intervals are typically 5-7 years for both.
Water Resistance
200m (20 ATM) vs 200m
The G-Shock GA-B2100 CasiOak is rated to 200m (20 ATM) while the Pro Diver Automatic 23681 handles 200m. Both offer identical water resistance ratings.
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 AmazonInvicta
Pro Diver Automatic 23681
Choose the Invicta Pro Diver Automatic 23681 if you value Automatic (Seiko NH35A) technology, Invicta (Japanese movement) heritage, and 40mm proportions. At $50–$100, the Automatic NH35A with ample power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Casio G-Shock GA-B2100 CasiOak and Invicta Pro Diver Automatic 23681 represent two distinct approaches to the diver category — the Casio bringing Made in Japan tradition while Invicta delivers Invicta (Japanese movement) 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.