Frederique Constant Slimline Moonphase Manufacture 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 (~$144) delivers Casio Quartz (Solar-Powered) technology at $4,156 less than the Frederique Constant Slimline Moonphase Manufacture (~$4,300). The Slimline Moonphase Manufacture justifies its premium with Swiss Made heritage and Automatic FC-705 (In-House). Both represent excellent choices in the luxury watch category.
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Specifications Compared
| Feature | Frederique Constant Slimline Moonphase Manufacture | Casio G-Shock GA-B2100 CasiOak |
|---|---|---|
| Price | ~$4,300 | ~$144 |
| Case Size | 42mm | 44.4mm |
| Movement | Automatic FC-705 (In-House) | Quartz Module 5611 (Tough Solar + Bluetooth) |
| Caliber Type | In-House Automatic Manufacture | Casio Quartz (Solar-Powered) |
| Power Reserve | 42 Hours | — |
| Water Resistance | 30m (3 ATM) | 200m (20 ATM) |
| Crystal | Convex Sapphire | 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
Movement & Performance
Automatic FC-705 (In-House) vs Quartz Module 5611 (Tough Solar + Bluetooth)
Wearability & Fit
42mm vs 44.4mm — different wrist presence
Value & Cost of Ownership
Casio is $4,156 more affordable
Water Resistance
30m (3 ATM) vs 200m (20 ATM)
Materials Face-Off
| Component | Frederique Constant Slimline Moonphase Manufacture | Casio G-Shock GA-B2100 CasiOak |
|---|---|---|
| Case alloy | Stainless steel 316L (standard mid-range Swiss spec) | Casio's proprietary monocoque case technology integrating carbon fibers into fine resin. The carbon fibers dramatically raise the tensile strength and modulus of elasticity of the case structure, allowing the GA-2100 to achieve an 11.8mm thickness — the thinnest analog G-Shock at launch — while maintaining full 10m drop impact resistance. Total case weight: 51g. |
| Crystal | Synthetic sapphire grown via Verneuil process, Mohs 9, convex (domed) profile, anti-reflective coating Mohs 9 | Flat mineral glass with Mohs hardness ~6. Thermally tempered for impact resistance — flexes under force rather than shattering like sapphire. Not scratch-proof, but replacement crystals cost ~$10. |
| Lume specification | None (dress watch by design) | Durable urethane polymer resistant to sweat, saltwater, UV radiation, and skin oils. Features quick-release spring bars. Known to last 5–10 years with daily wear before degradation. |
| Dial finishing | Silver lacquer with applied indices and printed moonphase graphic + pointer date scale | Secured by 4 Phillips screws for 200m (20 ATM) water resistance. Houses two SR726W silver-oxide button cell batteries accessible for user replacement. |
| Strap | Black or brown calfskin leather with signed Frederique Constant buckle | The luxury MRG-B2100 variant ($3,500+), hand-assembled at Yamagata Casio's Premium Production Line (PPL) by certified "Medalist" craftsmen, uses Cobarion® (cobalt-chromium alloy, 4× harder than pure titanium) bezels and DAT55G titanium (3× harder than pure titanium) bracelet links. |
Cost of Ownership Compared
The Casio G-Shock GA-B2100 CasiOak saves you $5,007 over 5 years of ownership
Who Should Pick Which
Pick the Frederique Constant Slimline Moonphase Manufacture if…
- Those who prioritize scratch resistance — sapphire crystal
- Dress watch seekers who want understated elegance
Pick the Casio G-Shock GA-B2100 CasiOak if…
- Anyone wanting an indestructible daily beater under $100 with serious design credibility
- Water sports enthusiasts — 200m WR with G-Shock shockproofing
- Watch modding enthusiasts — massive aftermarket ecosystem of metal conversion kits
- High-end collectors needing a dedicated beater alongside their luxury pieces
Frederique Constant Slimline Moonphase Manufacture
- Brand recognition below heritage Swiss brands — Longines (1832), Omega, Tudor have stronger name recognition. FC (1988 founding) is a younger brand without the same cultural footprint despite genuine in-house horological credentials
- 42mm wears large for traditional dress watch — modern preference is often 38–40mm for dress; 42mm + slim bezel pushes visual presence larger
- 21mm lug width awkward for aftermarket strap fitment
- 30m WR limits to pure dress use — no swimming, no shower
Casio G-Shock GA-B2100 CasiOak
- Stealth-black legibility deficit: The GA2100-1A1 has absolutely no Neobrite luminescent paint on hands or indices. Low-light readability is poor — you must rely entirely on the Double LED Super Illuminator.
- Mineral glass scratches: Not sapphire. Daily beater use will accumulate minor scuffs over time. Replacement crystals are cheap (~$10) but require caseback removal.
- Tiny digital subdisplay: The LCD window at 4:30 is small and genuinely difficult to read for anyone with less than perfect vision. The Hand-Shift feature (sweeps hands to 7:35 position to clear the LCD) helps but isn't a substitute for a full digital display.
- Module 5611 is quartz: For mechanical-watch purists, this is a non-starter. For everyone else, it's a feature — better accuracy (±15 sec/month), no winding, no expensive servicing, and 3-year battery life.
Our Verdict
Frederique Constant
Slimline Moonphase Manufacture
Choose the Frederique Constant Slimline Moonphase Manufacture if you prioritize In-House Automatic Manufacture engineering, Swiss Made craftsmanship, and 30m (3 ATM) water resistance. At ~$4,300, it delivers Automatic FC-705 (In-House) with 42 Hours 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 44.4mm proportions. At ~$144, the Quartz Module 5611 (Tough Solar + Bluetooth) with ample power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Frederique Constant Slimline Moonphase Manufacture 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.
Frequently Asked Questions
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