Foreground color = white
Background = black

2 Draw a Rounded selection using the following settings:

Selection Type = Circle
Feather = 0
Antialias = checked

Save current selection to Alpha Channel (Selections>Save to Alpha Channel) and name it Sphere

3 Fill the current selection with Sunburst Gradient Fill

Fill Style = Sunburst Gradient
Blend Mode = Normal
Paper Texture = None
Match Mode = None
Under the "Flood Fill Options" apply these settings:

Gradient = Foreground-Background
Repeats = 0
Horizontal = 30
Vertical = 50

NOTE: The Gradient Center assumes the position of the light.  You may need to play around with the "Vertical" and "Horizontal" settings value

 - O R -

Add a new layer (Layers>New Raster Layer)

Set your foreground color to brown (or any color you like)
R = 111  G = 88  B = 63

Fill your selection with Solid Color

Fill Style = Solid Color
Blend Mode = Normal
Paper Texture = None
Match Mode = None

Change current layer's blend mode properties to Color (Layers>Properties) Blend Mode = Colors
(Remember to experiment with the blend mode settings)

Load the Sphere selection from Alpha Channel (Selections>Load from Alpha Channel)

Apply the "Eyecandy Water Drops" filter (Image>Plugin Filters>Eyecandy 3.01>Water Drops) and follow the settings here.

Note that I have to decrease the selection by 3 just to capture the sphere portion.

Download 3dspheres Tube Pack
3dspheres.zip 133kb