What is a reasonable offer for a cleaned coin? Does it decrease the book value by 50%? Ebay sellers often ask book or higher and will not budge.
It depends on the severity of the cleaning in my opinion. Something that is harshly scrubbed with hairlines will loose much more value than something that is only over-dipped. Also, the remaining eye appeal will play into the factor as well so there is no general rule of thumb across the board.
As SensibleSal said. If all was the same I would not pay full price for one unless there was never going to be another option. What someone asks never guarantees true worth.
The chances of such a piece being in a slab, which the thread title refers to, would be very remote, though. Of course I am assuming the slab reference in the thread title means a reputable TPG. As to cleaned coins in a slab, most have been. It of course is just degree and time and lack of severity that allows the piece to be graded by the TPG and not returned with unfavorable results, meaning no wampum for you. Just an opinion.
This is absolutely the answer. I have cleaned and/or otherwise damaged slab coins. And the eye appeal combined with the value of the coin play into it. My favorite coin is a five figure coin that I acquired for less than half of the listed value. Eye appeal was beautiful and the damage was very minimal... But the label described the damage. My gain as I could care less..... But it all entirely depends upon what one is willing to pay. Monetarily, I would treat a $75.00 cleaned half differently than I would treat a $2500.00 cleaned 1795 dollar.
According to my old LCS, you should just charge the regular retail price and see if someone bites, haha... Like others have said, the answer to your question depends on the specific conditions of the coin, rarity, etc. A heavily polished Washington Quarter that someone has sent in to a TPG because it was "shinny" is not the same as an over-dipped Lafayette Dollar. Kind of like toning - some toning is undesirable according to current standards and will detract from the price. But some toning is extremely desirable and will multiply the price many times over.
From what I have seen in the eBay sales history, cleaned coins generally sell for less, the % depends upon the quality and rarity.
I assume you are referring to coins slabbed by one of the four TPGs in a Details holder that in one way or another says "Improperly Cleaned" and that you are referring to US coins. If you're asking about World or Ancients, stop reading now. Other posters have covered things like eye appeal, etc. so I will cover another aspect for coins that retain some eye appeal: If it is a common and inexpensive coin, then the value is somewhere between 5% and 30% of what you are calling "book" and I assume you mean something like Greysheet or CDN CPG. Say something like a 1917, Type 1 Standing Liberty Quarter in "EF-Details, Improperly Cleaned". If the coin is relatively common but very popular, like the Lincoln 1909 S VDB, then the value is somewhere between 25% and 75%. If the coin is rare but there are few collectors so demand is low, like the 3CN series, then the value is probably 15% to 50%. Now, if the coin is both rare and popular, like rarer early copper or scarce die marriages of Capped Bust Half Dollars, then the value is probably 40% to 100%+ of auction prices for non-details coins. Disclaimer: Percentages recited above are just my SWAG based upon my market observations and have no more validity than anyone else's opinion. So, the real answer to your question is that there is no real answer that applies to every or even most instances. You have to do your research and figure it out for yourself. But here's a tip: The "book" doesn't list prices for Details coins, but auctions sell details coins all the time. Heritage, DLRC, GC and others will let you look up auction results. This is probably the best way to figure out the market value of non-standard coins. And if a dealer won't accept your offer, walk away, there's always another damaged coin available somewhere for a better price.
