GH isn't really ideal for this kind of stuff since you easily need millions or billions of polygons for detailed displacement and GH does not handle this gracefully.

ZBrush is one of the best tools in that area and handles insane amounts of polys:

http://pixologic.com/zbrush/features/HDGeometry/

Many renderers can handle displacement rather well at rendertime but not many of them allow to export the finely detailed render-mesh.

Any specific reason why you want to do this in GH? Rhinos built in Displacement can do it and you can export the Rendermesh at a given resolution if I remember correctly.

Cheers,

Tom

Hi Kim - since you are planning on using 3D printing to make your design I'd like to suggest an alternative approach: Make the basic part (the glass in your case) one part, and then make the bumps (or whatever other decoration you want) as a separate part. Then, when you print, you can combine the 2 parts and they will print as one. 

A second benefit of this approach is that you can print with 2 different colors and/or type of filaments. (Of course this assumes your printer has dual extruders.) So your basic shape (the glass) could be one color (perhaps transparent) and the decorations could be a totally different (and perhaps non-transparent) color. 

The 2 photos show a small table lamp that has 2 such parts; the images are from Simplify3D which does a nice job of handling 2-color prints.

Rhino itself has ApplyDisplacement to bake a displacement map and create a mesh from a model.

http://docs.mcneel.com/rhino/5/help/en-us/commands/applydisplacemen...

Along with the ability to edit maps, it may be useful.