Before Ferdinand Schirnböck became the master engraver of the Austro-Hungarian Empire, he spent a few years in South America, engraving for the then newly founded South American Bank Note Company in Buenos Aires, Argentina. His main output while there concerned the large Argentine definitive series of famous personalities, which was introduced in 1888.
To be fair, he was probably 'only' responsible for the portrait vignettes, as the company also employed frame engravers, but information on this is of course a little hazy.
Nevertheless, it's a great set to collect, although a rather challenging one. I've been trying for quite some time to get together a set of mint stamps in reasonable quality with reasonable centring, and it's proving rather hard! In fact, I've nowhere near succeeded yet.
But thankfully, the enormous bonus with this set is that the proof material is so much less scarce than the actual stamps and in most cases very affordable. In case of the higher values even much more affordable than the stamps themselves.
And so, colour proofs made from the printing plates abound, and even the odd die proof may not be that hard to find.
But it gets better: there are, as far as I could find out, nine designs for which proofs exist but which were eventually not issued as stamps. Always fascinating material, of course, but even the majority of those are quite easy to find. The nine unissued values are:
Small format: 15c, 20c, 24c, 25c, 30c and 90c
Large format: 2p, 10p and 50p
With a little patience, you can put together a great collection of this set which shows material you won't always be able to include otherwise, and which forms an important part of the early career of Mr Schirnböck.
One word of caution though: Twentieth century reprints exist which are not always printed in recess. These, however, are always on paper, varying from thick to very thin. So if you want to be relatively sure you're opting for the real thing, then only try and find proofs which are on card!