Embr (JP)

To earn a diamond, you must either complete a weekly, complete all missions in a neighborhood, or salvage a blue stack of cash in a mission. I have never found one in a rescue mission, but I have found a few in safes during other mission types. Once you have one, head to the shop to buy something with it! You can get a skin for the starting axe for just one diamond, or buy something else by adding money to the diamond, like the vacuum grenade I suggest.