I couldn’t achieve the effect using Blender 2.79.
Here are some tests.
Test 01: The mesh is completely transparent even with has some color.
– Shader: Transparent BSDF
– Transparency: Mask
– Image: Blender2.79_TransparentBSDF_01.jpg
Test 02: The mesh looks transparent black even when it has a cyanish color applied.
– Shader: Transparent BSDF
– Transparency: Z Transparency
– Image: Blender2.79_TransparentBSDF_02.jpg
Test 03: Same result as the previous test.
– Shader: Transparent BSDF
– Transparency: Raytrace
– Image: Blender2.79_TransparentBSDF_03.jpg
Using Principled BSDF never showed transparecy at all in Blender 2.79