I don't know about the biggest diamond but the biggest vein in general was one that was clumped all together. i just had to excavate it.
Quote from ZyperPL »
Not necessarily. I've come across Gold, Iron, and Coal all directly touching each other, so this isn't that far of a stretch, although it is VERY unlikely. (There's a much larger chance that he just placed the gold and Iron there after he found coal and diamond.)