When mined without Silk Touch, diamond ore drops a single diamond. The maximum amount of diamonds dropped can be increased with Fortune . Fortune I gives a 1 ⁄ 3 chance for 2 diamonds, averaging 1.33 diamonds, Fortune II gives a 25% chance (each) to give 2 or 3 diamonds, averaging 1.75 diamonds, and Fortune III gives a 20% chance (each) to ...