Frederique Constant Classic Quartz Moonphase vs Casio G-Shock GA-B2100 CasiOak
Frederique Constant's dress watch meets Casio's diver
Quick Verdict
The Casio G-Shock GA-B2100 CasiOak ($100–$150) delivers Casio Quartz (Solar-Powered) technology in the tier below the Frederique Constant Classic Quartz Moonphase ($1,000–$1,500). The G-Shock GA-B2100 CasiOak measures 45.4mm (48.5mm lug-to-lug, 11.9mm thick) and is rated 200m (20 ATM). The Classic Quartz Moonphase justifies its premium with Swiss Made heritage and Quartz FC-206. Both represent excellent choices in the luxury watch category.
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Specifications Compared
| Feature | Frederique Constant Classic Quartz Moonphase | Casio G-Shock GA-B2100 CasiOak |
|---|---|---|
| Price | $1,000–$1,500 | $100–$150 |
| Case Size | 40mm | 45.4mm (48.5mm lug-to-lug, 11.9mm thick) |
| Movement | Quartz FC-206 | Quartz Module 5689 (Tough Solar + Bluetooth) |
| Caliber Type | Swiss Quartz | Casio Quartz (Solar-Powered) |
| Power Reserve | Battery | About 7 months on a full charge without light; about 18 months in power-saving (Casio) |
| Water Resistance | 50m (5 ATM) | 200m (20 ATM) |
| Crystal | Anti-Reflective Sapphire Crystal | Mineral Glass |
| Case Material | Stainless Steel | Carbon Core Guard Resin |
| Origin | Swiss Made | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Frederique Constant's design language vs Casio's approach
The Frederique Constant Classic Quartz Moonphase features a Stainless Steel case at 40mm with Anti-Reflective Sapphire Crystal protection. The Casio G-Shock GA-B2100 CasiOak offers Carbon Core Guard Resin construction at 45.4mm (48.5mm lug-to-lug, 11.9mm thick) with Mineral Glass. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Quartz FC-206 vs Quartz Module 5689 (Tough Solar + Bluetooth)
The Classic Quartz Moonphase runs the Quartz FC-206 (Swiss Quartz, Battery power reserve) at standard frequency. The G-Shock GA-B2100 CasiOak uses 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) reserve) at standard. The G-Shock GA-B2100 CasiOak offers a longer power reserve.
Wearability & Fit
40mm vs 45.4mm (48.5mm lug-to-lug, 11.9mm thick) — different wrist presence
At 40mm, the Classic Quartz Moonphase wears more compactly on smaller wrists compared to the G-Shock GA-B2100 CasiOak at 45.4mm (48.5mm lug-to-lug, 11.9mm thick). Water resistance differs: 50m (5 ATM) vs 200m (20 ATM).
Value & Cost of Ownership
Casio sits in the lower tier
The Frederique Constant Classic Quartz Moonphase sits at $1,000–$1,500 and the Casio G-Shock GA-B2100 CasiOak at $100–$150. On the specs that outlast any price: the Classic Quartz Moonphase uses Anti-Reflective Sapphire Crystal with Battery, against Mineral Glass and About 7 months on a full charge without light; about 18 months in power-saving (Casio) on the G-Shock GA-B2100 CasiOak. Service intervals are typically 5-7 years for both.
Water Resistance
50m (5 ATM) vs 200m (20 ATM)
The Classic Quartz Moonphase is rated to 50m (5 ATM) while the G-Shock GA-B2100 CasiOak handles 200m (20 ATM). The G-Shock GA-B2100 CasiOak offers superior water resistance.
Our Verdict
Frederique Constant
Classic Quartz Moonphase
Choose the Frederique Constant Classic Quartz Moonphase if you prioritize Swiss Quartz engineering, Swiss Made craftsmanship, and 50m (5 ATM) water resistance. At $1,000–$1,500, it delivers Quartz FC-206 with Battery power reserve.
Check Price on AmazonCasio
G-Shock GA-B2100 CasiOak
Choose the Casio G-Shock GA-B2100 CasiOak if you value Casio Quartz (Solar-Powered) technology, Made in Japan heritage, and 45.4mm (48.5mm lug-to-lug, 11.9mm thick) proportions. At $100–$150, the 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 makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Frederique Constant Classic Quartz Moonphase and Casio G-Shock GA-B2100 CasiOak represent two distinct approaches to fine watchmaking — the Frederique Constant bringing Swiss Made tradition while Casio delivers Made in Japan 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.