@thomthom said:

You can do the same without a texture, use white Fog on black geometry.

Hey, that's even easier. Thanks.

But aren't white areas usually interpreted as higher than black. I seem to get the right result with black fog on white geometry.

I believe this is the procedure:

1. Make a rectangle with a greyscale texture in the z direction, scale it to 1.001 to ensure the top face is white

2. Make the texture a projection
   

3. Select and apply the texture to the model
   

4. Set the time to noon, date to 3/21, location to near the equator (in File, Geo-location). Set light & dark to 100

5. With a parallel projection and no edges, the top view is your bump map
   

Great to find this Normal Map script. Thanks.

I found that slows down if you have the Materials Windows open to "In Model" textures. So remember to have that closed.

Was there any way to get a bump map from this ruby? I found some threads relating to bump mapping in Sketchup, but nothing conclusive, unless I missed it
http://forums.sketchucation.com/viewtopic.php?f=180&t=18024&start=15
http://forums.sketchucation.com/viewtopic.php?f=180&t=16660&hilit=plugin

My model would not export some surfaces to Google Earth .kmz

Turned out that only certain colours were failing to export. They were all renamed colours, appearing in my "In Model" colour set.

I tried updating to Sketchup 8.0.11752, and renaming the colours again, but it didn't work. Tried "fixing" the problem in the model-info menu but that didn't work.

Thanks to your hint, I edited the RBG by one notch and it fixed the problem. Don't know why or how my colours got corrupted.