Description (From Recipaedia)
A block of diamond. Extremely valuable, contains multiple diamond crystals combined into one large block. Good for decorative purposes. Be careful, because diamond is flammable and will burn when touched by magma or set on fire by lightning.
Combine 9 diamonds to form 1 solid diamond block.
The block may be later broken down to retrieve the 9 diamonds.
Diamond blocks are primarily used as decoration or building materials. Their extreme strength provides ultimate protection where explosion resistance is beneficial. However they must be protected from lightning and fire.
They are found in the CONSTRUCTION section of the recipaedia.
They only stack up to 4, so are not a very efficient means of storing diamond at 36 crystals per stack.
Unlike the diamond ore, this block can be successfully mined with any tool or by hand.