What is the value of an 1877 US 50 dollar gold piece?

Answer 1

The US never issued a circulating $50 coin. The only official $50 gold pieces were commemoratives struck in 1915 for the Panama-Pacific Exposition.

You may have a replica coin, a privately-issued piece, or a fantasy item. Please post a new question with more details that might help to ID it.
The US Mint did not produce a $50 gold coin in 1877.

Maybe not. Although at the time there were many producers of legitimate tender. Although a standard was sparse and counterfeiting was plenty. Do not buy replicas or clad. Same thing, fakes. Best wishes.

Actually 2 were produced and sold by an employee of the US Mint illegally. So there is actually 2 of them out there and I would imagine they would be priceless!

Okay, yes.....there were only 2 of the 1877 $50 experimental Gold Coins ever minted. Yes they did not go into circulation.....were STOLEN as part of an "illegal" sale. So as for being "priceless".....sorta. They have NO value because they are stolen from the mint. They STILL belong to the mint. If they ever come out of black market and the whereabouts become known they will go back to the mint. And either put on permanent display or melted. *I have heard that the mint CAN make an option to sell (has been done before) coins like these under certain circumstances. Althought it is very unlikely. Other experimental coins have been stolen before.

You guys are encyclopedia's of misinformation. There were indeed two of the the 1877 $50 coin coins minted. The mint director disappeared with them. Shortly after that they were returned to the mint and have resided, both of them, in the Smithsonian. They are, without a doubt priceless. It is called a half Union. A Union ($100) was supposed to have been minted but the half Union was such a failure it never was.