C4/C4NE 1950 Commemorating Inauguration of People's Republic of China. (Scott 31-35, Yang C23-26).One of the early PRC-sets where it is very important to distinguish reprints from originals, for originals are far more valuable: hundreds of dollars for a mint set, and sometimes even a 1000 for the NE (Northeast China)-set. Be very alert, for reprint sets are sold as originals by fraudulent or uneducated sellers.
The design is very nice, and I like these brightly coloured Mao-stamps a lot. I only have reprints, but it's about time I buy some originals. Only used ones of the C4-set are affordable, though... Am hoping to find a NE mint original in collections, but they indeed are rare.
There are 4 stamps to a set:
PRC: 800/ 1000/ 2000/ 3000
NE: 5000/ 10.000/ 20.000/ 30.000

A nice set of mint originals, worth hundreds of dollars!
Values for the set:
PRC: Originals mint 400 dollar, used 75
NE: Originals mint up to 1000 dollar, used 700
PRC: Reprints mint 20 dollar, used 12
NE: Reprints mint 20 dollar, used 12
One difference is very clear:
Perforation Original 14, Reprint 12.5 (24 perforation holes horizontal vs. 21 reprint)
The second difference is also clear, but hard to see on pictures:
Collar button of Mao has no dot in originals, a clear dot in reprints.

The dot in the collar button of reprints.
It is said there is a third difference:
Dot between the two 4-numerals below the denomination (indicating what stamp it is, thus 4.4-1 etc.): hardly visible in originals, well visible in reprints.
To be honest, my reprints show this visible dot, but I also have a definite reprint with NO dot at all. '

'

Visible dot between the two 4-numerals.

A reprint with no dot at all... As if it's not complicated enough already!
Used stamps: Reprints almost always have a light CTO-cancellation (there are very few examples of reprints postally used). Originals have the usual heavy, black, smudgy cancels of that period.

A genuine original, postally used, in the usual terrible state. Covers with stamps from this set are very sought after and thus carry an inflated price!

Two reprints with the usual light CTO-cancellation. Note the clearly visible dot between the 4-numerals: If this difference is really 100% genuine, it's an easy way for distinguishing reprints from originals.