Well, who's present that's still kicking at the end of the book?
Harry
Eldest Gruff
Sanya
Michael
Marcone
Ivy
Hendricks
Gard
Tessa
Nic
Rosanna
Deirdre
An Army of Worthless Mooks Who Would KILL to Get a Coin for Themselves
Thomas, Molly, and Murphy aren't around.
Nic was on the boat, and seemed genuinely surprised that Harry didn't have the Coins, so I'll rule him out.
Deirdre was a bit busy with the whole murdering Harry thing.
Michael and Sanya just... no.
Ivy was out of it, pretty much unconscious.
Marcone works for Marcone, and I believe him when he says he doesn't know.
Hendricks... I don't think he'd pick up a Coin. A) he's too smart for that, and B) he's too loyal to Marcone for split loyalties with anyone else (except for Gard, because he totally loves her.)
Gard might be interested in it for simple information gathering purposes, but I'm not sure she's really capable of doing something that might compromise her loyalty to Vaderrung.
Harry doesn't remember picking it up if he did it at all.
That leaves Tessa, Rosanna, Eldest Gruff, and an Army of Mooks Who Would Kill to Get Their Hands on a Coin.