- "Ness! Greetings! I'm George, Gerardo Montague's brother. Gerardo is in his mine, but he hasn't found any buried treasure yet. We did, however, find a Diamond instead. Gerardo told me to give it to Ness. Here it is... please take it. Well, I've got to go... I'm busy working at the other mine... busy, busy, busy!"
- — George Montague
The Diamond is a key item in EarthBound. After defeating the five Guardian Diggers who are guarding the underground mine in Dusty Dunes Desert, George Montague gives Ness a Diamond on the bridge between the desert and Fourside as thanks for getting rid of them.
When the Runaway Five end up in debt for the second time, this time at Fourside's Topolla Theater, Ness and co. give the Diamond they received to the theater's manager, who releases them because their debt is now paid off. She says, "That Diamond is worth maybe... MAYBE... $50. So I gave you a bargain." This is likely untrue, because the Runaway Five's debt was stated to be one million dollars, which is further implied by her heart loudly beating shortly after saying this.