Diamond Dust is a form of in-game currency in Modern Combat 5: Blackout.
Diamond Dust can be used to purchase items from the Black Market, such as weapon blueprints, mod kits, killsigns, and weapon camos. It can also be used to refill Suit Abilities as well as purchase Boosters for Boosted Events.
Players earn Diamond Dust upon completion of multiplayer matches. Likewise they will receive Diamond Dust when they purchase packs (such as Combat Packs or Weapon Packs) and receive duplicate items of those they have already earned (e.x. receiving a duplicate Skullbrush body camo from a Combat Pack will result in the player being awarded an amount of Diamond Dust instead).
In addition, when playing as the Bounty Hunter class, the player earns a Diamond Dust "bounty" for each kill, as well as for picking up dropped weapons in-game, which can either be accumulated until the end of the match, or used to refill grenades or deploy Military Support. Players whill kill a Bounty Hunter will also receive a Diamond Dust bonus based on the current size of its "bounty".