I wrote this on another forum, but decided to post it here to help some folks who might have questions about this. I decided to create a write-up about cleaned coins. Every day, I see more and more cleaned coins being posted on the forum by new collectors. Often, these cleaned coins are sold as Uncirculated or high grade coins. People new to the hobby will often purchase these coins at bargain prices hoping to get a great deal. Instead, they receive a coin that has been polished, dipped, or harshly cleaned. This guide will help new collectors distinguish cleaned coins from coins with original surfaces. I posted this in the Classic and Colonial Coins forum, as most of the cleaned US coins I see are classic coins. What Does It Mean When a Coin Is Cleaned? A coin that has been cleaned has been, well, cleaned. It has usually been dipped in a cleaning solution, scrubbed with a brush, or wiped with a cloth. A cleaned coin is usually worth less than one that has not been cleaned. It also usually has less eye appeal than un-cleaned coins. Never clean a coin unless you are conserving it with a chemical like acetone, or you know exactly what you are doing. Types of Coin Cleaning There are several ways that coins are cleaned. Here is a list of the most common ways, and terminology. Overdipped: An overdipped coin means that the coin was dipped in a cleaning solution for too long. A coin can be dipped properly many times and not be considered cleaned - it might look completely normal. However, when a coin is dipped for too long or dried after the dip improperly , the luster or toning might start to be stripped. This method of cleaning will often remove luster/toning from an AU/Uncirculated coin, and strip off the "gunk" on a worn coin. The coin might have reflective surfaces as well. Whizzed: Even though whizzing is technically not considered cleaning, I will include it here as it can be a bit difficult to spot for someone new to collecting, and alters the surface of the coin - often used to give a coin "artificial" cartwheel luster. A coin that has been whizzed has been "whizzed" by a wire brush rotating at a high speed. This will create many small hairlines on the coin. The whizzed coin may appear to have an odd pattern of luster, and many hairlines when rotated under light. Improperly Cleaned: This category covers several methods of cleaning. Often, coins in this category will have large hairlines on them from being cleaned with a wire brush, lack of luster, or an odd color. Proof coins that have been buffed with a microfiber cloth, and as a result have fine hairlines, also fit into this category. Examples of Cleaned Coins Coins with incuse hairlines that are parallel to each other almost always signify that a coin has been cleaned. A note about hairlines - There may be raised hairlines on a coin, known as die polishing lines. This means the die used to make the coin was polished. These lines from polishing of the die often will appear on a coin's surfaces - but they will be raised hairlines, unlike cleaning, which often causes incuse hairlines. The presence of die polishing lines does not have anything to do with a cleaned coin - this is just a note on how to distinguish the two. Here is a coin with a lack of any toning (or luster) around the devices, even though it's definitely worn. Most likely this coin was cleaned with a wire brush: Remember that a well-circulated coin will usually lack luster. If a coin that appears to be worn down to, say, Very Fine, but appears shiny or prooflike, it is most likely cleaned. On the other hand, an AU/Uncirculated coin should have luster. If it doesn't, that points to the coin being cleaned. This coin has an odd color from being cleaned, most likely from being dipped. It also lacks original mint luster: This coin appears shiny, but has no original mint luster. Remember that not all luster is the same. A coin may be shiny and have luster, but it may not be original mint luster. For example, the above 1900 dollar has luster - just not the original mint luster. The lack of original mint luster on a higher-grade coin often points to improper cleaning or an improper dip, which can strip mint luster from a coin. Copper coins will often acquire a pink color if they have been cleaned. I have cleaned a common date Lincoln cent to show what a cleaned copper coin will look like: Halos Around Devices - Does This Mean a Coin Is Cleaned? The short answer: Not 100% of the time. The long answer: Halos of toning around devices (stars, portrait, date, etc.) can signify that a coin has been cleaned, and the cleaning did not reach into the corners of the devices. However, it often just means a coin has a "crusty" patina on it. Therefore, if a coin exhibits signs of a cleaning (hairlines, lack of luster) and has halos around the devices, we can say that the halos were caused by a cleaning. However, if a coin exhibits no signs of a cleaning except for halos of toning around the devices, then we can say it most likely hasn't been cleaned. TPGs, Market Acceptable Cleaning, and Buying Coins Online When first purchasing coins, it is best to start off by only buying coins certified by one of the four (reputable) third-party grading companies. They are PCGS, NGC, ANACS, and ICG. Other grading services do not have as good of a reputation, and might over-grade coins or grade cleaned or damaged coins with a straight grade. You might see a coin in a third-party grading company's holder that appears to be cleaned that does not have that noted on the slab. You might wonder "Why didn't they say "Cleaned" on the slab?" Many times, this is because they thought the cleaning was market acceptable. This means that they thought the coin was not cleaned harshly enough to warrant a "Details - Cleaned" grade, or a coin has been exposed to the environment and has toned, therefore hiding the cleaning. A coin like this may straight grade one day at a TPG and might receive a "details" grade another day. A coin may be graded with a "Details" or "Genuine" grade. This means the coin has a problem - whether it is cleaning, damage, altered surfaces, or whizzing, etc - and the third party grader has deemed this problem to not be market acceptable. Purchase these coins with caution, as you may have trouble selling them if you decide to do so in the future. Remember - "buy the coin, not the holder." Make sure to examine all coins carefully before buying them. When purchasing a coin online as a new collector, it's best to buy coins certified by PCGS or NGC. However, don't just assume the coin will be un-cleaned and look like the assigned grade in hand. Make sure you examine the coin carefully on the photos. Check for all the items listed above (hairlines, lack of luster on AU/Unc. Coins, shiny coins that are heavily worn, etc.). Unless the photos are of excellent quality, then it may be hard to analyze the coin from the photos. Well-known dealers on eBay will often use high-resolution, clear photos. Note: Conserving Coins A note about conserving coins: To conserve a coin means to remove grime off the surface of a coin without changing the coin for the worse. For example, acetone can be safely used to remove organic matter on coins without damaging the coin being conserved. This is different than cleaning a coin, which alters the metal on the surface of the coin for the worse. Note that conservation will not remove evidence of a cleaning on a coin. Hope this article helped you understand cleaned coins better, or if you are new to collecting, help you understand how coins are cleaned and how to avoid them. Thanks for reading.