Spotting Cleaned and Dipped Coins
In the coin market of today you need to be aware of a great deal of factors if you intend to be a successful collector, no one likes getting the wool pulled over their eyes. So it is always good to be aware of techniques and processes which people may use to alter the appearance of a coin.
Unfortunately it has been known for collectors to fall on bad luck and encounter less scrupulous or uninformed sellers and pay over the asking price for something that appears to look shiny and nice, or of value and merit, has the appearance of great luster and tone, but to then find out that the purchase is overvalued and the coin has been tampered with.
Now just to make it clear, it may be particularly appealing for a collector to wish to bring a coin back to its original glory, but I would rarely recommend that you do this. Dipping and cleaning coins is a dangerous game and will result in devaluation. There is a huge price discrepancy between an original coin that has not been touched and one that has been altered in any way!
Few circumstances warrant the cleaning of a coin and I will list those that do later.
Coins cleaned with a cloth or polished can lose anything from 20% to 25% in value if not more! Be warned!
Typical methods of cleaning are as follows:
Using metal polishes and cleaners, toothpaste, acidic condiments, baking soda, soap, scrubbing with any abrasive cloth or rag or wizzed (tooled) using hand held electronic devices such as a dremel. Bleaching, greasing and oiling. Laser cleaning and ultrasonic cleaning.
Now you may be asking yourself why this is so bad, what could be wrong with such processes?
Are we not attracted to all that glitters and shines?
When a coin is cleaned the process removes its natural patina as well as removing layers of metal. This essentially damages the coin beyond repair! What you take away you can never give back!
To give clarity the word patina is used to describe changes to the surface layer of metal on a coin. This layer changes over the course of time as a result of interactions with environmental agents or contaminants. This interaction takes time and gives coins a unique appearance. In numismatics the word patina is often synonymous with the use of the words tarnish or toning.
Most collectors prefer to have coins with patina and it can take a great number of years to form this unique aesthetic and it can be removed in one miss judged moment.
People have used various methods to attempt to restore or upgrade coins over the years and the majority of processes leave some very obvious tell tell signs.
How to tell if your coin has been tampered with:
Cleaned coins often have a dulled but bright appearance that will look out of place in comparison to a well circulated coin.
You may see the appearance of greater than natural lustre on the coin, especially if it is old.
Do not expect to see reflection in old coins, they should appear dimmed and darkened.
The cartwheel lustre is not visible, coins that have not been tampered with should have a cartwheel of lustre when you inspect them. This should be especially evident in uncirculated coins! Expect to see radiating lines in a circular pattern. This should only be visible when the coin is turned.
Silver coins of age will look grey but with black build up around the detailing, this is an obvious sign of tampering. The patination can appear inconsistent as well as the toning. Watch out for old flashy white silver worn coins as these are most definitely tampered with. Remember metals tarnish so look out for such examples and compare!
If the coin has a flat luster but yet is dated it has probably been dipped, most coins will have a frosty, smooth or glossy lustre if they are untouched and you can easily see the difference.
Wizzed or tooled coins can be detected by small abrasive marks on the surface of the coins, often the finish will be mirrored. Marks may appear across the entire surface or just in a specific area. Often magnification is needed in order to detect such marks and it is highly recommended that you invest in a decent x10 microscope.
Tampered copper coins of age will appear to have a pale orange hue not the classic orange or red which they are known for. They may also have a grainy quality and can be spotted when compared to an original.
Sometimes you will find old cleaned coins, these will have been cleaned in the past and left to acquire a re tone whilst in storage. These coins will often appear to have a shiny lustre under the tone and may catch you as having an odd combination of qualities.
The more you explore the world of coins the more accustomed you will become to such signs and traits.
It can be difficult to pick up such signs when buying coins online and ebay is notorious for low quality images and dubious sellers. Remember always do your research when confronted by a new prospective seller. Look at reviews and ask for high quality images if you are not satisfied.
It is always good to have reference coins for comparison and if you feel the wish you may conduct small tests at home to examine the effects that coin cleaning can cause.
If you do wish to find out for yourself first hand the effects of coin cleaning if you are new to numismatics, I would advise using modern low value coins and a microscope to see the effects that these techniques cause. Once you have an eye for the different tampering practices it should ensure greater success at telling the unfettered from the tampered.
Now I would like to point out that you can have an exception to the rule.
There are only three instances that I would ever justify when it comes to coin cleaning and these are as follows:
If you have PVC damage on a coin from storage, whoa betide! This is avoidable use non PVC storage devices!
This requires the use of acetone, be careful use gloves and a cotton bud. Ensure you are in a well ventilated space and do not use nail polish remover buy acetone!
The coin has dirt or has built up debris on the surface. If this is the case I recommend holding it under cool distilled water for a brief period of time no longer than a few seconds and patting it dry with a soft cloth.
You have an ancient coin that needs to be identified. Leave the coin in a beaker of distilled water for a number of days no longer than a week, then proceed to soak in olive oil for up to a month. This should remove unwanted residue and any build up without having to result to abrasive or detrimental cleaning techniques.
I hope this information helps if you are new to collecting!
Remember it's all about having that eye for detail, finding reputable suppliers and taking your time! Ask for high quality images if buying online and make sure if you are buying graded coins the third party is recognised and legitimate. No camera tricks! Look for a good supplier and recognise the real from the phony.