Diamond

Diamond is a gem found deep underground, rarely appearing closer to the surface. The blocks they come from look like stone with little light blue gems in them. They are the most valuable gem. There is a chance of discovering a larger pocket of diamonds containing about 20-60 in one spot. It is also found in underground snowy biomes, often mistaken for snow blocks.



Trivia

 * In real life, diamonds are a clear and usually colorless gemstone. In Terraria both the rocks they are mined from and the mined gems are cyan blue, mostly to increase their visibility. This suggests that diamonds in Terraria contain boron, as boron absorbs lower-energy red light, the light that streams through has a blue hue. Despite this, the six color specific items that can be crafted from it appear white. This however changed in 1.2, where they appear as a colourless gemstone. Oddly, the diamond is now in the shape of a finely cut one, despite being mined beforehand.
 * The slight blue tint may reference Minecraft diamonds, which occur as aqua-blue gems.