Officially designated as 2000-W Sacagawea dollars, the coins were struck in 22-karat gold in the late 1990s. “These are now tied as the most valuable U.S. gold dollars struck since the Civil War and the most valuable space flown federal coins sold at auction. They are also the most valuable Sacagawea dollars ever sold, even surpassing records for the rare Sacagawea quarter.”According to the Professional Coin Grading Service (PCGS), the space-flown, 22-karat gold Sacagawea dollars are ranked #5 among the Top 100 Modern Coins. These gold coins are ranked #5 among the Top 100 Modern Coins. “These space-flown 22 Karat gold Sacagawea dollars transcend any single collectible category and stand as true American treasures.”The Sacagawea dollar coins that were in wide circulation in the early 2000s feature a portrait of Sacagawea on the obverse or “heads” side.