Stamps (Philately)/Expert Profile

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I am a collector of United States postage stamps, and also a stamp dealer. I`m a member of the American Philatelic Society (APS). My principle area of interest and expertise is in United States Stamps.

Experience in the area

I've been selling stamps on the internet since early 1996. I maintain a stamp web page that concentrates on mint US stamps issued generally between 1890 and 2009. I'm an active seller on since 1996, under the user id "mleon". You can find my web page at


I have a Bachelor of Science degree in computer science from the University of Nevada at Las Vegas, 1984.

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Richard10/23/16101010Thank you, Mark. I didn't find this .....
Prashant S Akerkar10/10/16101010Dear Mark Thanks. Prashant
David09/25/16101010Mr Leon,
Kathy08/28/16101010Mark Leon is a 10 for sure .....
william08/06/16101010Thank you for your answer, I have .....

Recent Answers from Mark Leon

2016-10-20 RF27:

Richard,    RF27, the blue playing card "1 pack" revenue issue from 1940, is valued at $3.00 for each fault-free, eye-appealing mint example.    -Mark Leon    I deal in United States Stamps  http://www

2016-10-16 Washington & Blue Oval Lincoln Profile:

Courtney Johnston,    Both stamps are common in used condition, and the unfortunate trimming of the surrounding paper so close to the design of the printed stamp, actually reduces whatever collectible

2016-10-09 Stamps printed on both sides.:

Prashant S Akerkar,    With regard to United States issues, there are no stamps where the design is printed on both sides (at least not on purpose).  However there are some commemorative and duck stamp

2016-09-21 10c US Int Rev Stamp, inverted:

David,    Your stamp is Scott number R109a, a "second issue" revenue stamp from 1871.  Its rare.  Fault-free, eye-appealing examples have catalog value of $2,000.  With the heavy pen cancel, I would estimate

2016-08-23 1980 olympic stamps and more:

Kathy,    Stamps on paper torn from envelopes like you describe is known in the philatelic world as "kiloware", because it changes hands based on value by the pound, rather than by individual stamp.  The


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