Help Identify This Phillipine 2 With Guam Overprint

Could someone please assist me with any information pertaining to this uunused Philippine/US stamp Jose Rizal 2 cent dark green ( Philippine Scott241) with over print expressing "Guam Guard Mail" in red with gum in back? Does this stamp overprint come in different color overprint other than red? Does the overprint have different markings that makes one more valuable than another? For example, with Hawaiian overprints, a dot or missing dot after last letter in overprint may make a difference with assessment of stamp. Is this the same with this specific stamp? What is the Scott # for this stamp?
This stamp was next another unused stamp of the same denomination in Philippine page within International Junior Stamp Album which I purchased recently. It has three areas noted on this specific stamp: Philippines, United States, and Guam which makes me wonder if this stamp may have value. Any information would be truly appreciated. I have not seen this overprint before on this stamp before. Thank you in advance.

It is a local post overprint. You can check the following for some basic background and info.

https://en.wikipedia.org/wiki/Posta...m_Guard_Mail
https://en.wikipedia.org/wiki/Posta...m_Guard_Mail

Google for addition information.

Your stamp is Guam #M7(29Dec1930) in the Scott US Specialized catalog.

This particular overprint on this stamp design also exists in black ink. For the red overprint, there is a premium variety of "GRAUD" and also "MIAL".

On cover examples of these locals carry a premium.

Thank you so much for your excellent references to review on line pertaining to this specific stamp. It is very interesting due to the issues of these stamps.
I went to purchase the Scott Specialized Book, another more recent one today. My other reference book did not have information about this stamp with an appearance markings of the stamp under Guam.
In Scotts it does not explain that the M1 can only be in black including claims there are counterfeits of overprint exist.So,I appreciate very much the information you provided. Thank you. Any collector needs to be advised to make sure to be careful assessing this stamp.
In my own opinion, after seeing the photos in Scott of the bold lettering design,the printer makes it look like a 3rd issue,but my appears to have a slight difference with the dot after the "L." The font dot looks like the first issue (M1)however after reading the article saying font was changed for the 3rd issue. The 3rd issue overprint of the original stamp looks like a curle between the lower "bottom of the middle of the "L"and not disconnect to the letter "L" design for the period after the letter "L".
Instead viewing my stamp, everything looks the same in my stamp except the period after the the letter,"L." The period dot looks the same as the M1 in black separated and has a space from the letter "L" which may not suppose to be like in the 3rd issue of the red overprints.I do not know if this slight change makes any difference for the 3rd issue stamps in red to be considered an error. Would appreciate any opinion on this specific observation.
Scott only specified overprint counterfeits in the M1 and M2 in black. They specifically mention that writing of font "Graud" and "Mial" in spelling errors are noted for the 3rd issue in red.
The M1 only (2000)done in April 1930 and with the 3d issue only in red was done in December 1930, (50,000) both had perforated 11 including unwatermarked.
I love learning about different markings with overprints ect. Thank you again for your wonderful information provided. I hope to hear a response also what I noted with the observation of this 3rd issued stamp.
Have a great day!
Blazenstar

There is no "period" after the "L" in either overprint. What you are seeing is the serif at the end of the leg in "L". When the overprint on the leg is light, the thinness of the middle part of the leg makes it appear like "l.", but it is "L" if you examine it closely.

Your stamp is not from the first series. The quick way to distinguish between the 2 overprints is to look at the "M" in "GUAM". In the 1st set, the middle of the M is very very high (almost missing, looks like a small divot). In the 2nd (black overprint) and 3rd (red overprint) sets, the middle of the "M" extend almost all the way to the baseline. That is why I IDed your stamp as Guam #M7 (3rd set).

Thank you for the information. Yes, I viewed other Guam Stamps and see the difference you are expressing. It is definitely a 3rd series. On ebay can see the different types being sold at the moment.I see the exact stamp being sold with a better view of the L and not missing the part of the ink like seen in this stamp. I guess the ink was not pressed hard enough to see the full view of the letter. Thank you for the information pertaining to the "M" to look at the other stamps for future references.Excellent information!

Thank you again for the Have a great day!

Note: Thread bumped, 5 years since last post.
Linn's Tip of the week.
Click to expand.