Casio G-Shock GA-B2100 CasiOak vs Invicta Pro Diver Automatic
Two divers compared — $100–$150 vs $50–$100
Quick Verdict
The Invicta Pro Diver Automatic ($50–$100) delivers Seiko NH35 Automatic (Hacking, Hand-Winding) technology in the tier below the Casio G-Shock GA-B2100 CasiOak ($100–$150). The Pro Diver Automatic measures 40mm and is rated 200m (20 ATM). 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 |
|---|---|---|
| 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 Seiko NH35 |
| Caliber Type | Casio Quartz (Solar-Powered) | Seiko NH35 Automatic (Hacking, Hand-Winding) |
| Power Reserve | About 7 months on a full charge without light; about 18 months in power-saving (Casio) | 41 Hours |
| Water Resistance | 200m (20 ATM) | 200m (20 ATM) |
| Crystal | Mineral Glass | Mineral Glass |
| Case Material | Carbon Core Guard Resin | Stainless Steel |
| Origin | Made in Japan | Japanese Movement (Seiko NH35) |
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 offers Stainless 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 Seiko NH35
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 uses the Automatic Seiko NH35 (Seiko NH35 Automatic (Hacking, Hand-Winding), 41 Hours reserve) at 21,600 vph (3 Hz). The Pro Diver Automatic offers a longer 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 at 40mm. Water resistance differs: 200m (20 ATM) vs 200m (20 ATM).
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 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 41 Hours on the Pro Diver Automatic. Service intervals are typically 5-7 years for both.
Water Resistance
200m (20 ATM) vs 200m (20 ATM)
The G-Shock GA-B2100 CasiOak is rated to 200m (20 ATM) while the Pro Diver Automatic handles 200m (20 ATM). 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
Choose the Invicta Pro Diver Automatic if you value Seiko NH35 Automatic (Hacking, Hand-Winding) technology, Japanese Movement (Seiko NH35) heritage, and 40mm proportions. At $50–$100, the Automatic Seiko NH35 with 41 Hours 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 represent two distinct approaches to the diver category — the Casio bringing Made in Japan tradition while Invicta delivers Japanese Movement (Seiko NH35) 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.