The Seagull ST2500 is a Chinese-made automatic movement produced by Tianjin Sea-Gull Watch Group as part of the ST25 series. In replica production, the movement appears as the ST2500 V2 — where the V2 designation indicates a replica manufacturer modification to the base calibre, typically involving adjusted finishing, regulated timekeeping, or case-compatibility changes made specifically for the replica application. The ST2500 is most commonly found in replica open-heart watches and diver configurations, where its open-heart capability and robust automatic architecture make it a practical choice for display-focused builds.
The ST2500 operates at 21,600 vph (3Hz) with a power reserve of approximately 45 hours and includes hacking seconds — allowing the seconds hand to stop when the crown is pulled, enabling precise time-setting. Its 30.4mm diameter and movement height ranging from 5.9mm to 7.9mm (depending on complication configuration) make it compatible with a range of case architectures. The open-heart complication — often positioned at 6 o'clock and described in replica listings as a "flywheel" display — is a cosmetic feature exposing part of the movement through the dial. This is a genuine visual complication, though the gravity-compensation function of a true tourbillon is not present.
Specifications
| Specification | Detail |
|---|---|
| Movement Type | Automatic mechanical |
| Calibre | ST2500 (ST25 series) |
| Jewels | 25–26 |
| Frequency | 21,600 vph (3Hz) |
| Power Reserve | ~45 hours |
| Diameter | 30.4mm (13.5 lignes) |
| Height | 5.9mm–7.9mm (varies by configuration) |
| Hacking | Yes |
| Winding | Bi-directional automatic |
| Open-heart | Yes — cosmetic display, not a tourbillon |
In Practice
- The V2 designation indicates a replica manufacturer modification to the base ST2500 calibre — not a factory version number from Seagull themselves. As with all V designations across replica movements, the specific changes vary by manufacturer and are not always publicly documented.
- The open-heart display at 6 o'clock is a genuine visual complication — part of the movement is visible through the dial cutout. However, it does not perform the gravity-compensation function of a true tourbillon; replica listings that describe it as a tourbillon are using the term incorrectly.
- The 21,600 vph frequency produces a slightly slower seconds hand sweep than higher-frequency movements — noticeable when compared to movements running at 28,800 vph, though well within normal range for daily wear use.
- In QC photos, the open-heart aperture alignment and the finishing quality of the visible movement components are the primary checkpoints — misalignment between the dial cutout and the movement's decorative elements is the most common issue worth flagging before acceptance.
- The ST2500 is considered a reliable workhorse movement within Chinese automatic production — durable, practically serviceable, and well-suited to the open-heart and diver watch builds where it most commonly appears in the replica market.
Related Terms
Automatic Movement · Hacking · Power Reserve · Exhibition Caseback · Skeleton Miyota 9015 Clone · Clone Movement · Tourbillon Inspired
Read Next
For a complete breakdown of the movements used across replica watches — including how Chinese automatics compare to Japanese calibres in daily use — see our Replica Watch Movements Explained →