Some dimes can be worth serious dough.

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If you have a rare 1894-S Barber Dime, congratulations -- you're sitting on nearly $2 million! According to Coin Values, the dimes were made as gifts for friends of the San Francisco mint superintendent.

A 1907 Barber Dime on an old and faded yellow envelope and a green textured antique book.

Credit: skhoward

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Credit: skhoward

Only two are in circulation, so the chances of you finding one are slim. But if you get your hands on one, you’ll be pleased to know it’s worth a whopping $1.9 million.

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While the 1894-S is by far the most valuable dime, it’s not the only one that’s worth a gold mine. Some dimes produced during the 18th and 19th centuries can fetch hundreds or even thousands of dollars, from the 1829 curl base “2” Liberty Cap Dime (worth $7,750) to the 1895-O Barber Dime (worth $385).

How do you know if your dime is old enough to be valuable? Here’s a hint -- it probably won’t feature Franklin Delano Roosevelt, who was president in the middle of the 20th century. While one so-called “Roosevelt Dime” (the 1968-S, no-S proof) is worth about $7,500, your run-of-the-mill, modern-day dime is likely worth a mere 10 cents.

Before Roosevelt became president, dimes featured "an impression emblematic of liberty," per the U.S. Mint.