Blender 3D: Noob to Pro/Every Material Known to Man/Marble

Marble 1

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Marble bowl

There are many different marbles out there, here is an OK one found by me.
Color: Red=0 Green=0 Blue=0
Under the "Map To" tab change the color to white(Red=1 Green=1 Blue=1)
Texture Type: Marble
Marble Settings:
Sharper
Harder
Sin

Marble / Alabaster

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Marble or Alabaster Mortar & Pestle

Here is a marble I made to use with a project. This one uses a perlin marble for COL and for NOR which gives both color and bump. Crucial to realistic marble of course is the subsurface scattering (SSS). I also added a bit of reflection which you can find on some marble, but usually not alabaster unless it has been very well polished.

The top row are the texture buttons, but bottom two rows are tabs from the material buttons, pulled apart so you can see all of the values.  

Adding more layers

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One way to make the marble look more realistic is to add more layers of the marble texture with slightly different characteristics. For instance, create another texture:
Marble Settings
- Sharper
- Soft Noise
- Tri
(Same settings otherwise, or add your own slight variation) You can try using a different Noise Basis, such as Original Perlin or Voronoi F3.