mAb MEM-G/1 is supposed to work well for IHC-paraffin. We list a couple of sources for this clone, plus many other possible Abs you may want to explore:
I would recommend an antibody database available at www.labome.com. For antibodies to HLA-G, you can follow this link: https://www.labome.com/gene/human/HLA-G-antibody.html. In particular, Santa Cruz Biotechnology offers mouse monoclonal 4H84 and MEM-G/1 antibodies to HLA-G for IHC on paraffin embedded sections. Also, both Invitrogen and Abnova offer mouse monoclonal MEM-G/1 and MEM-G/2 antibodies to HLA-G for IHC on paraffin sections. In addition, BD Biosciences has one mouse monoclonal 4H84 antibody to HLA-G for IHC. I hope this comment is helpful.