Three chinese cash coins, identification help needed.

I have these three Chinese cash coins, but they seem to have some kind of black stuff on them.  Are they genuine or tourist trinkets?  If they are genuine what ones are they specifically?  

They're all approximately 24mm in diameter.  Bottom left is 2.3g top is 3.28g bottom right is 2.35g.  

Bottom right looks like N#135231 but if so it's very underweight.

Thanks in advance.

Huangsong TB - seal script - North Song

Hongwu TB - Ming

Frenchlover

Huangsong TB - seal script - North Song

Hongwu TB - Ming

 

Thank you.  

The top i think thats Huangsong Tongbao - Northern Song Dynasty - Seal Script

The bottom left i think thats Hongwu Tongbao - Ming Dynasty - Regular Script 

The bottom right i think thats Taiping Tongbao - Northern Song Dynasty - Clerical Script