Scott numbered it 245-248a, China catalog C33M Scientist of Ancient China, issued Aug.25, 1955.
Not that it is made with great perfection, but for 1955 year, ethnology level, printing machines, color quality etc, this issue can be named like best -of-the-best!
Simple design give even more beauty to this m/s, and portrait are fine balanced.
here come persons on stamp:
Tsu Chungchin (429-500), mathematics
Chang Heng (78-139), astronomy,
Chang Siu (683-727), astronomy,
Li Shin-chen (1518-1593), physic & pharmacology.
All four stamp are face valued of 8f, at this time standard rate for all China stamp, and with this magic number "8" that characterized China effort in all field of life, from planning economy to the simple day-life.
One color, gravure, paper choice - give just "taste" in Philately, and in wish to include it in every serious collection. Catalog value as in Scott or in China catalog from 1998 and 2006 year, give nice value of 90-100 US$ per set, in mint condition - but if we go to explore little auction houses and eBay, we will discover very fine rise in prices. I see that on market, prices ranged around 300+ US$ per set of four m/s and set in mint condition - this is very nice investment opportunity, even today when we have "great recession"!
Overall feeling for this country philatelic material are and this period - simple, buy it at first glance! mint, used, CTO - don't think twice - even if market will go down, and prices will drop (that I can not see in near future), material will be more and more rare! Too many are going back to mainland, too many collectors in China want this period, material back to collection and offer are near minimum, that what I see on market are very-very high prices!
Right from SG #17 edition catalog, I see that it have 27.00 BP per set and 225.00 BP per four sheets, on China web - it have very great shortage in stock, and single that was available in 2007 year was sold same moment when offered, at the time it was sold for 16.00 $ per set and 144.00 $ per m/s.