“International Labour Day on May 1st” (“五一世界勞動節”)

Yang NE24-29, J.DB-39

Perforated:

10 元 ⦿ [Yang NE24]

30 元 ⦿ [Yang NE25]

50 元 ⦿ [Yang NE26]

Vertical imperforated:

10 元 [Yang NE24a]

30 元 [Yang NE25a]

50 元 [Yang NE26a]

Imperforated stamps (on silk thread paper with watermark):

10 元 [Yang NE27]

50 元 [Yang NE29]

Imperforated stamps (on newsprint paper without watermark):

30 元 [Yang NE28a]

50 元 [Yang NE29a]

Imperforated stamps (on silk thread paper with watermark), proof prints:

10 元 [Yang NE27b]

50 元 [Yang NE29b]

First Day Cover (FDC):

First Day Cover (rate of 45 元 for double registered letter).
Cancel: 1 May 1947, Harbin [inner city] (哈爾濱中央大街),
Binjiang Province (濱江省) [ex. Akio Furusho]

Rear side
 
 

Remarks (in general / for this issue):
– All commemorative stamp issues from Northeast are rare on commercial covers.
– Shifted perforation and large stamps with “wings” can be found commonly.
– Because of the existence of large stamps (inaccurate line perforation) and imperforated margins single “imperforated” stamps can’t be count as imperforated stamps.
– Imperforated stamps are more rare as partly perforated stamps (Yang NE24a-26a). So please be careful for altered “imperforated” stamps out of partly perforated stamps. 
– Single imperforated stamps on newsprint paper or black proof prints count as imperforated stamps because they were not produced with perforation.
– The watermark is rather big structure, so stamps without a water mark can be found commonly.
– From time to time you can see various black proof sheets on thicker newsprint paper often in reverse or inverted printing and / or in combination with different values / sets (like the one shown in Yang catalog page 118). Sometimes also printed on thick watermark paper. A valuation is hard to calculate, often the authenticity is just doubtful, if sold the price not seldom exceed 10.000.- USD, but please handle these proof prints very carefully!