Spain Alfonso XIIi "Cadet" 15c 1901-1905 Specialized Classification

I would like to show you this group of Spanish stamps of Alfonso XIII "cadet" 15c 1901-1905, they are not stamps that I like very much….. but I have been finding them little by little, until I have gathered enough to make an interesting classification. My stamps do not stand out for their aesthetic beauty philatelically speaking, but sometimes not discriminating beauty allows you to form beautiful historical groups (also philatelically speaking) like this one….
In the Scott and Edifil catalogues, they give for this model 3 different numbers SC#275/77 and Edifil SC244/246 (I don't know if in the specialized catalogues this number increases, since they are not within my reach), but in reality there are some more shadows, which give it a much juicier point, in addition its classification is much more interesting using its control number printed on the back, and the 6 different impressions that were made of it.
There is a lot of interesting information about this in these studies:
http://www.filateliaincidental.net/...dete002b.htm
http://www.filateliaincidental.net/...adete001.htm

Here is the summary of the classification:

1st printing: made up of blackish blue stamps with blue control numbers between 000,001 and 665,000, approximately, which began to be used on January 1, 1901;
2nd printing: made up of stamps that began to circulate in 1902, mauve in color with blue control numbers between 665,001, approximately, and 999,999;
3rd printing: also from 1902 and composed of lilac-brown stamps, but this time with green control numbers between 000,001 and 645,000, approximately;
4th printing: composed of lilac-brown stamps that began to circulate in 1904, with blue control numbers again and between A.000,001 and A.750,000;
5th printing: violet stamps with blue control numbers between A.750,001 and D.205,000, approximately, that began to circulate in June 1905;
6th printing: bluish-violet stamps with blue control numbers between approximately D.205,000 and D.500,000, which began to circulate in June 1909.

I hope you like it, I am personally very happy to have collected them and to be able to see them together, and even find some rare ones like the green control number with a letter, or follow its continuity on the date of its cancellations.

This is a very nice grouping Murasama. I like the research you did on this particular stamp and how you categorized them by color, date, and number. Thanks for posting this.