go into it and find a corner with a small hole. Jump in and walk a little; the game will teleport you to the Upper Skylands. From here, head to the second island of the Upper Skylands, where you will see a big temple. Inside the temple...
Certain randomly-generated structures can spawn with diamonds inside. The desert temple and jungle temples both have a chance of generating between one to three diamonds inside of chests. The Woodland Mansion, which is in the dark forest biome, may contain a certain room that holds a solid bloc...