Casio G-Shock GA-B2100 CasiOak vs Orient Sun & Moon
Casio's diver meets Orient'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 Orient Sun & Moon ($250–$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 Sun & Moon counters with Made in Japan craftsmanship and 50m (5 ATM) water resistance. Both are exceptional watches for their respective tiers.
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Specifications Compared
| Feature | Casio G-Shock GA-B2100 CasiOak | Orient Sun & Moon |
|---|---|---|
| Price | $100–$150 | $250–$500 |
| Case Size | 45.4mm (48.5mm lug-to-lug, 11.9mm thick) | 41.5mm |
| Movement | Quartz Module 5689 (Tough Solar + Bluetooth) | Automatic Caliber F6B24 |
| Caliber Type | Casio Quartz (Solar-Powered) | Orient In-House Automatic (Hacking, Hand-Winding) |
| Power Reserve | About 7 months on a full charge without light; about 18 months in power-saving (Casio) | 40 Hours |
| Water Resistance | 200m (20 ATM) | 50m (5 ATM) |
| Crystal | Mineral Glass | Mineral Glass |
| Case Material | Carbon Core Guard Resin | Stainless Steel |
| Origin | Made in Japan | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Casio's design language vs Orient'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 Orient Sun & Moon offers Stainless Steel construction at 41.5mm with Mineral Glass. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Quartz Module 5689 (Tough Solar + Bluetooth) vs Automatic Caliber F6B24
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 Sun & Moon uses the Automatic Caliber F6B24 (Orient In-House Automatic (Hacking, Hand-Winding), 40 Hours reserve) at 21,600 vph (3 Hz). The Sun & Moon offers a longer power reserve.
Wearability & Fit
45.4mm (48.5mm lug-to-lug, 11.9mm thick) vs 41.5mm — 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 Sun & Moon at 41.5mm. Water resistance differs: 200m (20 ATM) vs 50m (5 ATM).
Value & Cost of Ownership
Casio sits in the lower tier
The Casio G-Shock GA-B2100 CasiOak sits at $100–$150 and the Orient Sun & Moon at $250–$500. 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 40 Hours on the Sun & Moon. Service intervals are typically 5-7 years for both.
Water Resistance
200m (20 ATM) vs 50m (5 ATM)
The G-Shock GA-B2100 CasiOak is rated to 200m (20 ATM) while the Sun & Moon handles 50m (5 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 AmazonOrient
Sun & Moon
Choose the Orient Sun & Moon if you value Orient In-House Automatic (Hacking, Hand-Winding) technology, Made in Japan heritage, and 41.5mm proportions. At $250–$500, the Automatic Caliber F6B24 with 40 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Casio G-Shock GA-B2100 CasiOak and Orient Sun & Moon represent two distinct approaches to fine watchmaking — the Casio bringing Made in Japan tradition while Orient delivers Made in Japan engineering.
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How This Page Was Made
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.