Many hobbyists, especially those starting out, cannot detect the 12 most common problems found on eBay, Proxibid or other online portals. With more coin sales happening now online, often with unreliable sellers who may or may not have any numismatic expertise, it is increasingly essential to identify problems before bidding and determine whether you can live with the flaw.

When I started collecting, I would ask my local coin shop dealers about how to spot problems. Later, coin club presentations helped me learn. However, with our busy lives and fewer brick-and-mortar shops in home towns, the best place to learn may be on the same platform that causes the confusion: Internet.

Below are problems with explanations about grade-ability and whether or not to bid:

ACID RESTORED

Typically you will find rare or scarce buffalo nickels with dates restored by acid. Because 5-cent Buffalo coins are 75% copper and 25% nickel, a common mixture of acid based household chemicals (don’t try it; don’t experiment) removes a thin layer of nickel to reveal the date, in this case a Type 2 1913-S nickel. These coins may be worth purchasing with low-ball bids if they are key dates, such as this 1913-S Type 2, or perhaps a 1918 over 17-D; but normally these treated coins have little worth and often just serve as hole fillers.

ARTIFICIAL TONING

Artificial toning is done by a variety of methods, from chemicals to heat, typically causing uneven colors that do not blend with luster as a natural patina might on a silver coin. Most artificially colored coins are common dates. If buying on eBay, check out the rest of the sellers items. If most of the selections are toned coins that look like this amateurishly colored one, be forewarned.

CARBON STREAKING

This is actually a flaw caused by the environment, ranging from bad storage in a damp place or in a smoker’s house. Sometimes the streak is really dark tone or grease residue. In any case, I have purchased coins like this and tried to remove the streak using acetone or a commercial dip, and have yet to be successful. A dip may remove the streak if it is toning. But I discourage viewers from ever dipping coins because of the potential harm it can do to the silver.

DARK TONING

Some patinas are plain ugly. Here’s an example, a Mercury dime that is uncirculated and may just be gem. But you wouldn’t know it from the dark tone. In this case, an expert numismatist using a diluted dip can usually restore the luster and brilliance. If you don’t know such an expert, don’t bid on the coin or be prepared for poor eye appeal. With any dip, you are taking a risk of damaging the coin. Don’t do it unless you’re an expert.

DIPPED COPPER

Never use a commercial dip to clean copper. If you do, you destroy whatever luster the coin had. Someone tried to clean this coin with a dip, probably to remove PVC damage, and striped it of its brilliance and worth.

EDGE MARKS

Edge marks occur when bagged coins jostle with each other and the rim of one rolls on the surface of another. Although this coin also has been polished, an edge mark by itself will not prevent a coin from being graded, although it will lose points on the Sheldon 0-70 scale.

PIN SCRATCH

A pin scratch is usually caused by someone misusing a stapler or opening a flip incorrectly. Unlike an edge mark, this will prevent a coin from being graded. Also, this type of flaw is the easiest to miss when buyers place bids too eagerly. (The scratch, by the way, runs from the liberty head band to the “L” in “Pluribus.”)

POLISHED

Polished coins are often passed off as proof-like or deep mirror proof-like. Polished coins are usually only worth the silver unless a key date or scarce variety. Here is an extreme example with a seemingly outrageous suggested retail price. My bid would be $18, not $72,000.

PVC DAMAGE

Acetone or a commercial product like MS70 removes PVC damage caused by keeping coins in old flexible plastic flips. Sometimes, however, as in this coin, the damage is so severe that the green areas are eating into the metal. The coin is not grade-worthy.

RIM BUMP



These are easy to spot if you assess a coin from the rim inward. Otherwise you can miss this flaw. A bump is serious and can render a coin ungradeworthy. (The bump here is to the left of the “1” in the date.) A rim bump differs from a rim nick (usually caused by the edge of a bagged coin jostling the edge of another). A grade from PCGS or NGC is possible with a nick, depending on how many dings a coin has.

STAINED

Silver can stain based on where the coin is kept, whether it has been cleaned and retoned in streaks, or what substance may have reacted with the surface. Sometimes a dip can remove the stain, depending on its nature. (I haven’t had much luck with coins like this and don’t recommend dipping anyway unless done by an expert.) The coin is not gradeworthy.

WIPED

You can see the wipe on the second star from the bottom swirling upward to the middle of Lady Liberty’s neck. Usually this type of mark occurs when someone tries to clean a coin with a tissue. Depending on the severity of the wipe, a coin may or may not grade (usually the later).

Certainly there are other flaws less common than these, including altered surfaces (difficult to detect when done professionally). But these 12 common flaws show up more often than not in an online auction. My rule when bidding on raw coins is simple. If I detect a flaw, I don’t bid. Period.

What are your bidding rules? Have you ever won a coin online only to encounter one of these flaws? Share your stories!



