When editing materials, you can link the specular color to the diffuse color.
To link the specular color to the diffuse color:
On the Resources tabs, click Materials.
On the Materials tab, click the material you want to edit. The Context view displays the details of the selected material.
If selecting a material with a face and back, ensure the side you want to edit is selected. You can click the material image under Face or Back to select the side. The selected side is highlighted in blue.
In the Specular section, select Diffuse Color.
The specular color is now the same as the diffuse color, and is linked to it.While linked, the specular color is locked. To edit the specular color alone, you must clear Diffuse Color.