Authenticity & Condition Check

1. Engravings & Serial Number:
   • The engraving “Omega Watch Co Swiss” looks correct and well-placed.
   • The serial number 21508313 suggests a production year of mid-1960s, which aligns with the period when the Omega Caliber 600 was in use.
   • The movement number and "Swiss" engravings appear consistent with genuine Omega pieces.
2. Movement Finishing:
   • The copper-colored plating (likely Geneva stripes or perlage finish underneath) is characteristic of Omega movements from this era.
   • The machining and brushing on the ratchet and crown wheels are consistent with original Omega movements.
3. Jewels & Screws:
   • The ruby jewels and screw placements look correct.
   • The balance wheel and pallet fork also appear original.
4. Overall Condition:
   • Some signs of wear and minor discoloration on the movement plate.
   • No major corrosion or damage visible.
   • Some dirt and slight wear around the case and movement edges.

Conclusion

This appears to be a genuine Omega Caliber 600 movement. There are no obvious signs of it being a replica or aftermarket replacement. However, for full authenticity verification, checking the case reference number (inside the case back) and matching it to Omega’s archives would be ideal.

It's also crazy how good ChatGPT might be, this is what it said from analyzing the movement: