"Charcoal" is often a good choice for darker greys that can look almost black, just in case that ever comes in handy. 

The "funny" thing about situations like this is that eBay are notorious for refusing to accept the seller's evidence (they say things like we can verify the listing image shows a grey jacket, but we can't verify you sent a grey jacket), and yet rarely - if ever - ask the buyer to even provide evidence. Let's say, just for the sake of argument, someone had a similar black jacket, and provided eBay with a photo of that instead, that really couldn't be called evidence either, because if they can't verify what a seller sent, then they can't verify what a buyer received, and logically have no place making a decision either way. 

But here we are 😞 I'd be very interested to know what kind of evidence eBay would accept from a seller. 

I watched a YoTube vid of a very angry US fellow, on the phone to eBay CS because he had a buyer claiming an item they bought wasn't genuine leather. Seller got the item verified as genuine leather by a third party, CS rep on the phone said they still can't give the seller the win because they may have taken a different item to get verified - why are these possibilities not considered when buyers are making accusations and claims? (Rhetorical question, sadly).