Grand Theft Auto V (Xbox One)

By far and away the easiest method of doing this achievement is on the Fleeca Job. Platinum Medals are awarded to whoever is in the driving role, both in the setups and in the Heist itself.

For the Scope Out mission its all on whoever gets in Lesters Car first.
For the Kuruma mission, it's not about the kills attained in the parking lot, it's about whether you drive the car or not.
The finale platinum is again going to the driver, the best way to assure this is by hosting the heist yourself.

After completion the Heist can be repeated every in game day which is 48 minutes real time. After the first instance of this heist the setup cost is $11.5k so its not to expensive and takes 30 minutes max to completion.

As Colour x Blind said in the comments you can check how many platinums you have by going to the stats section, then awards and then looking for the award titled Decorated.

Hirsute Dave has added that if you want to go through the rest of the heists, these are the roles you have to partake in them.


Prison Breakout
(Bus) - killing the escort helicopter seems to be the difference maker
(Plane) - kill the most Vagos, flying the plane also helps
(Police Station) - retrieving the Casco from the cargo ship
(Wet Work) - recovering the documents from the lawyers
(Finale) - the Prison Officer gets it more often than not (I've also seen the Demo team win it)

The Humane Labs Raid
(Valkyrie) - be the pilot
(Finale) - be the pilot
(Codes) Kill the most FIB agents
(Insurgents) Drive the regular Insurgent (i.e. the unarmed one)
(Hydra) Fly the Hydra
(EMP) hack the door

Series A Funding
(Steal Coke) Get the most kills (being in the aerial assault might help)
(Trash Truck) Grab the most trash bags OR Drive the truck and get kills
(Bikers) Kill the most bikers and drive one of the vans
(Steal Weed) Man the technical gun (you'll need to be one of the lookouts)
(Steal Meth) Kill the most O'Neills (driving the tanker can't hurt either)
(Finale) Man the technical gun again (the North Side team probably have a few more targets too)

Pacific Standard Job
(Vans) Be a Navigator and grab the target van once you know which it is
(Signal) Deliver Avi - this means you need to be the closest to his hut after killing all the police on the island (or after the inevitable restarts) so that he follows you
(Hack) Be the Transporter
(Convoy) Either deliver the cargo truck or jump on the Insurgent gun - I've seen both work more than once thoughso I suspect how many Merryweather guards you kill also count
(Finale) Be the Hacker or Demolitions (basically so you're carrying the cash)

Big Thanks to Hirsute Dave on the info for most of the other heists. If any of these seem to be incorrect please comment and I'll edit accordingly.

Update 19/05/2015 - zsoltee53 says "The achievement's counter is buggy, not moving from 0%. Check your progress here: MENU / STATS / AWARDS / HEISTS / DECORATED

When you completed a Heist, quit the game and restart, so you can replay the Heist without waiting 48 minutes."

If you don't mind the short wait between replays, you can replay the first heist, the Fleeca Job, with a friend over and over.

Simply host the heist replay yourself and invite your friend it, and upon completion, have your friend host the heist and invite you in.

Each player can only host the same heist replay once, and then they have to wait an hour, real time, before they can host it again, so taking it in turns with your friend to host the heist replay allows you to get up to 6 Platinum medals every hour (3 missions, 2 people hosting).

To gain the platinum medal, do the following for each set up mission and the finale:

1st Setup Mission (Scope Out): Make sure you drive, the driver always receives the Platinum medal.
2nd Setup Mission (Karuma): Drive the Karuma, but make sure to also kill a decent amount of the enemies, as if your friend kills enough, s/he can steal the platinum medal from you.
Finale: Be the driver, the driver always receives the Platinum Medal.

Do this 4 times and you'll only need one more platinum medal for the achievement.

First of all platinum medals across heist Setups and finales will be only counting from Fleeca Job to Pacific.
Medals from doomsday heists will not count.

Try to do this achievement after u will do all the heists and get rest of achievements for them.

The easiest way is to do Fleeca job as it required only 2 people and it is very easy.

You need to be a driver in every setup and in Final to get platinum.

1 Setup - Be a driver, do not damage "granger" to get platinum.

2 Setup - Drive the black kuruma after you will stole it.

Final - be a driver and u gonna get platinum.

Good luck!