I can't answer this one but since no one else has, I'll try to help.
Did you ask the contractor for an explanation of Gem Seal? What I found on the WEB is that Gem Seal is 'provided' by local/area companies for driveway sealing. Maybe these local/area companies pay a royalty for the 'ingredients', or something.
I did find this on the WEB. I can't explain it but may you can talk to the Contractor about it.
We use the finest coal tar emulsion manufactured by Gem Seal, Inc. Coal tar is a closed ring hydrocarbon which for the most part does not oxidize when exposed to weathering or chemicals.