Scott Stamp #613

I have two Stamps that look very alike #610 and #613 I took a pic of the #610 and posted it as #613 I think I have the #613 is there any thing I can look for before I re-list the stamp. I did not mean to list the wrong stamp any help from here would be great. I have over 50,000 stamps pre 1940's and have been looking to sell half of them thank you

#610 is a flat press stamp and #613 is a rotary press stamp. They are different sizes which are listed in Scott's. To find a #613 is extremely rare and if you ever think you have one then you should get it certified by an expert - APS or PSE. If it comes back as a #613 by a very lucky chance, then ebay, Delcampe and any other online do it yourself auction is not the way to go. Send it to someone like Regency, Shrieves, Siegel or the like who have a strong reputation and buyers with deep pockets.
Will

Here's a great link for all to help with the subject much more than I can elaborate:
http://www.1847usa.com/identify/YearSets/1923.htm
Scroll down to the Harding issues.
Will