What does gold proof fdc mean?

"Gold proof FDC" refers to a specific type of coin that is both gold and minted to a proof standard, meaning it has a high-quality finish with a mirror-like surface and sharp details. "FDC" stands for "First Day Cover," indicating that the coin is often released in a special presentation on its initial issue date. This combination signifies a collectible item that is both valuable due to its gold content and sought after by numismatists for its quality and presentation.