GTA 5 Diamond Casino heist

Diamond Casino heist is currently the best payed heist in GTA 5. If you take all the stuff inside The Vault you can get from 2.2 milions to 3.2 milions.

How to start :
First things first, you will have to pay quite big amount of money for starting this hiest (1million or more, depending on which arcade you choose) . As first, you will have to purchase Arcade from Maze Bank (GTA in-game website). Players can unlock the new Arcade Business property by meeting Lester in Mirror Park.

Scope out casino :
 First of all (after you purchased Arcade) you need to gather information (pohotos) about the casino. You will have to scope few main locations and cameras, but you can also scope more of them, what will give you more options and will help you in finale. (YOU DON´T NEED TO DO THIS PART AGAIN AFTER COMPLETING HEIST)

Scope the vault contents (check for what objective you´re going)
After you scoped the casino, you need to search what is in the vault. It´s just a short mission (5-10 min), that will show you what target are you going for, it can be : 

CASH - Highest propability, but it will give you least money, 4 people needed to take it all - 2.2 mil
GOLD - High propability, if you are doing it with 3+ players you can get about 2.5 mil money (3.2 mil with glitch)
ARTWORK - Less propability, you can collect all of them even you are only 2 players - about 2.6 mil
DIAMONS - Very low propability, 3 players needed to take them all - about 3.2 mil

After you scope casino and its vault, you choose your approach:
Silent & Sneaky - Enter the casino stealthy, don´t let anyone see you (EMP prep recomended) , use silenced guns
Big Con - Enter the casino pretending you are staff, exit the casino by changing your clothes to fireman/agent (exit disguise prep needed)
Aggresive (also called "Loud") - Fight your way through the casino straight to the vault and out. (dugan shipments prep recomended)

Preparation :
After you scoped casino, its vault and chose the approach, you must complete 6  main preparations(preps/set-ups), but you can also do extra 6-7(depending on approach) preparations, which can help them in finale. 

Heist Prep missions will change, based on the heist approach chosen by the group leader, and which ones are completed will determine the various bonuses, equipment, weapons, vehicles, and crew they will have access to in the Heist Finale. Players will be able to select their Heist Crew based on various factors, with each one contributing a particular skillset to the job.

Crew: People (abstract, they are never actually seen or heard in the heist) that help you with your heist. They take commision from the total value of the money you make (better skill = higher take)

Hacker - The most improtant person of the crew, he gives you time in the vault - Avi Shvartzman is the best one (if you dont have him unlocked then Paige Harris), Avi takes 10% of the money you get but he gives you 3.30 minutes in the vault (Paige takes 9% but gives only 3.15 minutes in vault)
Gunman - Not that important, because you don´t actually shoot in Big Con and Silent & Sneaky, in Loud micro SMG will be fine. (Cheapest gunman=5% recomended)
Driver - Not that important if you dont allert cops, if you do you can go to underground tunnel and loose them (Cheapest driver=5% recomended)


Finale - Once players have picked their approach and completed prep missions, the Heist Leader can initiate the finale. The Heist Finale requires 2-4 players to initiate. After finalizing details and choosing the location of the Buyer, the Heist Finale will begin. This stage will vary wildly based on the approach chosen, the particular intel players gathered, and the equipment obtained during the Setup phase.

Video guides :
How to unlock Avi Shwartzman - https://www.youtube.com/watch?v=lDQ-EdynQtI
Best way to do Silent & Sneaky approach - https://www.youtube.com/watch?v=oSkiN_sdg1Q
Best way to do Big Con approach - https://www.youtube.com/watch?v=EWoUImiVDUo&t=238s
Best way to do Aggresive(Loud) approach - https://www.youtube.com/watch?v=Dm76g0fFOQc

BONUS - You can steal daily earnings of the Diamond Casino  that "have not been sent to The Vault yet" as a Lester (the guy who is organizing this whole thing) said. You can find daily earnings in big safe. One player must hold green button in the office (see image) and other player goes inside the safe.

IMAGE TAKEN FROM GTABOOM (if you want to know more information make sure you check they´re website)

My opinion :
Personally, I like this heist much more then others, because it´s different. It has bigger payment, which is more real for robbery and it has specific style of way you do it. You can do it anyway you want, you don´t have to follow the steps like on other heists.