The conversion process utilises various Visual Effects. Shininess can be controlled from the materials tab.
For very dull, flat surface effect, set specular color to mid-level gray, and shininess to zero. For a sparkly metallic shiny surface, set specular color to strong golden color, set shininess to 25.0.
If you have a 3D model with a texture, and you wish to see the texture image with minimal distortion due to lighting effects, then the controls that should work to show the best texture are to specify overrides for all of ambient, diffuse and specular. Set Emissive or Ambient to full white, and drop diffuse and specular to black.