Evaluate the coin

If you want to sell it as real coin, what kind of story you would tell to explain denomination that did not exist.

If coin is real and it is just the problem with your photo converting 5 to 3, then you are not showing mintmaster details on other side and they can alter coin value.

It looks genuine to me, but the second digit of the denomination has been manipulated so that the 5 was turned into a 3.

Manipulation may have taken place very long ago.

It is not a very uncommon date, nor is it of outstanding quality (F+ or VF-). Post mint manipulation may further repell buyers. Something in the 10 USD magnitude, I would say.

N#22182

What is the size and weight? Does it match to the 15 kopecks one?

This coin was found long ago in the Sumy region, in the village of Ugroedy. It was found in a house built in the tsarist era, dating back to the 1800s. The village's history tells us that Kharitonenko, the owner of a sugar factory, lived there. It is also known that Kharitonenko traded with the Poles. The coins were minted in denominations of 13 kopecks, equivalent to one zloty. There is no doubt about the coin's authenticity. It was found by an ordinary villager living in the house.

tatti9

This coin was found long ago in the Sumy region, in the village of Ugroedy. It was found in a house built in the tsarist era, dating back to the 1800s. The village's history tells us that Kharitonenko, the owner of a sugar factory, lived there. It is also known that Kharitonenko traded with the Poles. The coins were minted in denominations of 13 kopecks, equivalent to one zloty. There is no doubt about the coin's authenticity. It was found by an ordinary villager living in the house.

1. Please cite a reference on coins minted in the denomination of 13 kopecks.

2. As best I can tell, the last time that there was a zloty equivalence, it was 15 kopecks not 13  N#23768

3. If you have no doubt about  the coin's authenticity, then the better approach might be to send it to NGC or PCGS for grading, which will enhance the coin's value when you go to sell it..

How many of these were found?  

Also, how long ago is “long ago”?  What year were these found?

I agree with tdziemia, you should submit it (or them) for grading to NGC.  You may also wish to contact Dmitry Markov.  I won't weigh in on authenticity, but NGC or Markov would be considered to be authorities on this subject.