What is the value of a 1933 US 20 dollar gold piece?

Answer 1

Because it's illegal to own one it's hard to put a hypothetical value on one of the coins but IF it were to come up for sale some guesses at a price have been around $10,000,000.

The 1933 $20 gold piece, or "double eagle" is one of the rarest and most storied US coin, on a par with the famous 1804 silver dollars. Over 400,000 double eagles were minted in 1933 but the US went off the gold standard before any were put in circulation. One example was saved to be put in the Smithsonian while the rest were supposed to have been melted. However, a handful were apparently taken from the Mint without official permission. One ended up in the hands of Egypt's then-king Farouk, and ten more were hidden in the safe deposit box of a Philadelphia coin dealer.

The Farouk specimen was allowed to remain in private hands after years of legal wrangling, but the Philadelphia coins are considered to have been stolen from the Mint and are the subject of a probe to determine their legal ownership.

Over the years many replica 1933 double eagles (with the word REPLICA or COPY on them) have been made as well as a lot of outright fakes, so it's important to be super-suspicious if anyone offers a supposedly genuine 1933 $20 coin for sale.