Although reprints for some values do exist prior to 1895 they are not noted in catalogs, except for the 1891 reprints on coarse paper. However, these are mostly of the higher denominations so a careful study of the 1c, 2c and 3c values will help the collector identify the paper and gum of the originals. Further, a close examination of the provisional issues prior to 1895 will assist collectors in becoming familiar with the characteristics of originals.
In 1895 a shortage of 1 centavo stamps led to the overprinting of the 12c, 24c, and 30c, while a shortage of 2 centavos stamps resulted in the 20c and 30c being overprinted to meet this need. Thus, originals of the 1c and 2c stamps are not common mint. A study of the various overprinted stamps will help collectors determine the original paper and gum of this issue and the shades of the 12c, 24c and 30c can be used to weed out originals from reprints.
The “First” Issue of 1896 has two shades of the 15c. Only the violet shade (on a gray-white paper) is an original. The 15c in bright ultramarine (on a white paper) is always a reprint on a paper similar to the originals. Use it to help determine what is an original and what is a reprint on a similar paper. The official stamps of this issue exist ONLY as reprints.
The “Second” and “Third” Issue originals are not easy to distinguish. The only overprinted value is the 15c on 24c provisional but it can be used to help distinguish the original paper and gum. The “FRANQUEO OFICIAL” overprint is on originals and some reprints so care must be taken with these.
The originals of the 1897 issues are on the same paper as the originals of the Second & Third 1896 issues although the gum now is now yellowish-white to brownish instead of colorless. However, there are a number of provisional stamps that can be used to help make a determination of what the originals are like. I refer to the 13c on 24c, 30c, 50c and 100c. Also, there is a distinct difference in color of the 24c. The best way to see this is to obtain a copy of the 13c on 24c provisional and use it to compare to the unoverprinted stamp. If the color is the same it is an original else it is a reprint.
The originals of the issue of 1898 are on the same paper as the Second issue of 1896 so they can be compared to that.