- Well-circulated (worn) condition: Around $1,300 - $1,600.
- About Uncirculated (AU) condition: Approximately $1,700 - $2,200.
- Uncirculated (UNC) condition: Roughly $2,500 - $3,500, depending on the specific grade determined by a reputable grading service like the Numismatic Guaranty Corporation (NGC) or Professional Coin Grading Service (PCGS).
However, it's worth noting that individual coins can sell for higher or lower prices in auctions or specialized coin markets depending on their individual characteristics and overall numismatic desirability. Consulting with reputable coin dealers or auction houses experienced in rare coins can provide you with a more accurate assessment of the value of a specific 1878 $20 gold coin based on its exact condition and market trends.