Washington Sc#213 Jumbo Size?

I've read a little about the Jumbo size, "Stamps with unusually large margins for the issue are often valued well in excess of normal margin copies…". Could I consider this SC#213 copy from my collection as Jumbo?

No. One jumbo margin is just a badly centered stamp.

Here is my #213 for comparison. The margins are not as big as your bottom margin, but they are larger than normal and equally balanced. I just wish the cancel were a bit lighter.

So, are both Jumbos? I would say yes...

No - yours doesn't have four wide margins.

Ok must be four

"OK, must be four."
So far so good. Dear Murasama, have you noticed connection with your comment on the 10c stamp with straight edge at left side? You said at one time, it could not be cut off because the margin was too big.
Now look at your example here, the bottom margin. It is very big! So, someone could have cut off the perforations neatly. One just has to remain open minded, and gain experience by looking at many examples.
Don't have access to many examples? yes we all do -- just review ebay listings on an occasional basis, for example. Hope these tips help.

I'm a newbie and I'm trying to learn, I half-way draw conclusions based on my own ignorance...."I heard bells but I don't know where." I hope the situation improves now that I have some catalogues, I got the standard 2017, specialized 2006, values 2010...many doubts will be covered and new ones will arise but I think that on firmer ground...Without a doubt this community and its members, with their patience, collaborate a lot yo my enjoyment and knowledge of the stamps

I agree that all four sides should be relatively equal and larger than normal in order for it to be a Jumbo, although I have seen "Jumbo" used for 3 large and 1 small in auction catalogs and other descriptions. To me, that is just an off-centered stamp.
You also have "Tall" normal sides but top and bottom are over-sized, and "Wide" top and bottom are normal but sides are over-sized. Many terms are in the eye of the describer with little standardization.