You will need a good magnifier, at least 7x or stronger (I recommend a 10x loupe that you can keep on your key chain.) If possible, it's best to save up several dollars' worth of coins and do them all at once, but these instructions will work for any amount.
- Sort your coins into groups by denomination - Always examine your coins in batches of like types. For instance, check all of your pennies, and then your nickels, then your dimes, etc. Your eye will get used to seeing each type after the first couple of coins, so you can scan them more quickly once your brain has "mapped the landscape," so to speak. Also, you are more likely to notice differences from one coin to another when you check them in groups of like types.
Don't get caught up in minutiae! If the doubling or other flaw is so insignificant that it is hard to see with a 10x loupe, it's usually not worth much.
- Examine the coin's obverse inscriptions - Look carefully for anything in the lettering that seems odd or unusual. Many doubled die varieties show doubling in only part of a word. Die abrasion, polishing, or greasy dirt collecting on the die face can cause letters to fail to strike up on the coin. Turn the coin around and look at it from different angles. Check carefully for missing letters, doubling, and other oddities in the inscriptions.
- Examine the date and mintmark - The date and mintmark should be a special focus of your attention, because these are among the most valuable errors you are likely to find in circulation. There are many things that can go wrong in this area, including repunched mintmarks and dates, overpunches, various types of doubling, and other errors.
Note: If the mintmark or date is on the reverse side of the coin, (or the edge, as on the Presidential Dollars) don't turn the coin over to check now. Wait until you get to the reverse, but do be sure to check carefully when the time comes.
- Examine the major devices and the coin as a whole - Take a look at the coin's major device, such as the portrait. Also consider the obverse side of the coin as a whole. Does it look right? Is there any obvious doubling anywhere? You want to look for die cracks, cuds, and missing elements. Pay close attention around the portrait's eyes, ears, mouth, and chin, looking for doubling. Be sure to look at the rim, too, watching for anything abnormal.
- Turn the coin over, checking the die rotation - Carefully and systematically turn the coin over from top to bottom (not side-to-side). If the coin was right-side up before turning it over, the reverse should be exactly right-side up as well. The U.S. Mint takes great care to ensure that the die rotation on U.S. coins is correct, so coins which are significantly out of rotation are fairly valuable errors. Get in the habit of checking rotation on every coin you handle. You especially don't want to miss the 180 degree rotation errors, as they are the most valuable of all!
- Examine the reverse - Following the same sequence as you used for the obverse, examine the reverse side of the coin, with the coin oriented upside down. Check the inscriptions and devices for any doubling, missing elements, or other oddness. Pay especially close attention to the mintmark, if present. Try tilting the coin at various angles to the light, which can sometimes make details easier to see.
- Check the edge - The final step in checking your coin should be to examine the edge. Roll the coin along your palm, so you can see all of the edge, while you watch for seams, lines, missing reeded edges, and other abnormal factors of the edge. If the edge has lettering, look for doubled or missing letters.
- Set aside anything that looks odd - Practice these steps until you can perform them very quickly. Each coin you examine should take no more than 15 to 20 seconds, and when you get used to seeing the detail on different coin types, you'll develop an eye for this that will allow you to scan coins even more quickly. Set aside any coins that you think might be different than normal, so you can examine them at your leisure under good lighting with strong magnification. At first, you might end up finding a lot of worthless varieties, but you'll be amazed at how much two seemingly alike coins can differ in the details!
- Don't get caught up trying to discern really minor details. If the doubling, or repunched mintmark, or die break cannot be seen easily and clearly under 10x magnification, the variety probably isn't worth much money. People typically pay the good money for varieties and errors they can see easily.
- Get in the habit of tipping the coin at different angles to the light. Sometimes minor doubling can only be seen from a certain angle.
- Get a couple of good reference books on error coins and die varieties written especially for beginners. For general information about mint errors and varieties, I recommend The Official Price Guide to Mint Errors by Alan Herbert.
Another excellent book for beginners is Strike It Rich With Pocket Change by Ken Potter and Brian Allen.
Both of the books I recommend are profusely illustrated with close-up images of what to look for on the coins, and both have rarity and pricing information. The first book is more of a reference for anything you might find, whereas the second book explains specific coins to look for.
What You Need
- Your daily pocket change (or buy rolls of coins to search!)
- A good magnifier or loupe, 7x power minimum, 10x preferred