Such excellent forgeries overprint exists for many years and it seems they appear again recently especially at Zhao auction. And the 昆明加盖改作票 as well, can find the forgeries overprint on Ebay and Zhao. Really want to know the source.
These forgeries are for collectors who DON'T have genuine refercence stamps ... that's the dirty trick and not all collectors are so skillful to judge such "better" forgeries.
I report them because I hope to avoid damage to other collectors.
@小卢
Please apologize, I don't publish this in public anymore. Always when I mention the mistakes and how to detect the forgeries a new generation of forgeries comes into the market which are more "perfect" and correct the mistakes I mentioned before.
I will send you an email to "lu888692@yahoo.cn" with scans.
Nice block sample with overprint shifted. Very good comparison of position 7, obviously as I mentioned, the image is too solid, too clean and looks like perfect. Just compare with the genuine one (your block), the printing color, shades, paper texture is more uneven and loose. Perhaps DFHK's expert had made a careless mistake
this time. What a pity, honest buyer!
@我要区票
Yes, good, you are right! It's a FORGERY! I just mention this example because NOT only the paper are important. This stamp tried to copy the position 7 in the sheet (left side of the double sheet of 9). Please compare this fake stamp with a genuine stamp from the same sheet position. To judge stamps also carefully look at the drawings.
The sample comes from this nice block with shifted overprint