What are the coins John Wick is using?

Question

In the movie John Wick, the title character is using some kind of gold coins to pay for cleaning his house or for the receptionist and to enter the bar.

So my question is: What type of coin is he using?

Answer 1

This is discussed in the one of the video extras that were released to advertise the movie.

In short, the coins were custom-made for the film and represent a secret currency used by the society of assassins (of which John is a member) with which one can purchase a variety of services including body disposal, medical care, accomodations and transport.

Quoting from the video linked about;

One side of the coin is Peace and Violence in one character, the other side is a Lion (for strength) and a Shield for protection because these coins, if you've got one, you're protected

Answer 2

The video link in the other answer no longer work, but after using the wayback machine to check an older iteration, we could see the page was titled: Exclusive clip: The assassin's code of 'John Wick'.

The video can be found on Youtube: John Wick (2014) The Assassins Code - Featurette.

The quoted passage in the other answer happens at 3:17:

Starting at 2:41, we get explanations as to what the gold coin represents in universe from various people who took part in the movie:

Adrianne Palicki (Ms. Perkins): Apparently, if you have a gold coin, you can pretty much get in [the Continental] and get pretty much everything you need.
Dan Leigh (Production Designer): The gold coins are, in a way, sort of the private credit card.
David Leitch (Producer): The gold coins are kind of like your entrance into the world. Not only do you have to have the wealth to... to be in this sort of underworld, you have to have that type of wealth where you can drop a thousand bucks and enter these places. But it's more like a membership.
Keanu Reeves (John Wick): We deal in a currency of gold. Gold coins are passed amongst us. This special group.
Adrianne Palicki (Ms. Perkins): You can get somebody to remove bodies for you, you can get a doctor that's not going to go to the cops.
Dan Leigh (Production Designer): That gold coin identifies them with each other and it's their way of moving through the process. One side of the coin is peace and violence in one character, and the other side there's a lion for strength and a shield for protection. Because these coins also, if you've got one, you're protected.

We are also given an explanation from Berrada in the third movie, around 52:50 into the movie:

Berrada: You see that coin? The first coin ever minted in this facility. Next to it, the first Marker. Not easy to track down, believe me. Now this coin, of course, it does not represent monetary value. It represents the commerce of relationships. A social contract in which you agree to partake. Order and rules.

Also, here's a picture of Winston holding a gold coin from the second movie, when John was paying him a visit as he was analysing gold coins to be put into circulation:

Here's that same picture, tilted to the left for convenience of looking at the coin. You may notice lines that look like those were 3D printed, unlike the ones from the other answer: