One Rupee Big Dabbu Issue Year 1980 Calcutta Mint Clock Rotation Error **Rare** Collectable Grade.

This exceptional 1980 One Rupee coin from the Calcutta Mint represents a significant find for serious numismatists. Struck in durable copper-nickel composition, this piece showcases a rare clock rotation error—a minting anomaly where the reverse die rotated during production, creating a distinctive misalignment that distinguishes it from standard issues. Issued during India’s post-independence monetary period, this coin carries historical weight alongside its numismatic appeal. The Calcutta Mint mark adds regional provenance, making it particularly sought after by collectors focusing on Indian coinage variations. Clock rotation errors are scarce in circulation-grade specimens, and this example’s collectible grade ensures both visual appeal and authenticity. Whether you’re building a comprehensive Indian coin collection, hunting error varieties, or seeking investment-grade rarities, this piece delivers documented scarcity and historical significance in one remarkable find.