Importing obj file: Is it not possible to keep the ngons?

When I import a diamond-shaped mesh generated in Blender, the ngons are automatically converted.
I’m not sure if it’s blender’s obj exporter that does that, or if it happens when I import the file in Rhino.
Is there a way to avoid this?
I need to re-export the mesh with the ngons ito Blender otherwise the material doesn’t display properly.
Here below is an image of the same meshe: the one on the right is the original, as generated by Blender, and the one on the left is after I’ve imported it in Rhino and then back in Blender. See the ngons have been converted.

Hello- AddNGonsToMesh should help - does that do anything you like?