[header] How to cut marble [title] Purchase or rent a large wet saw with a diamond blade. [substeps] You can also use a reciprocating dry diamond blade, but you risk shattering the marble. Put on protective eyewear, hearing protection and gloves before you start cutting. 
[title] Ensure you have a water supply and check the water pump on the saw. [substeps] Water keeps the blade from overheating, protecting the blade/saw and the marble.