Mesh faces are not oriented the same way

Hi,

I'm trying to create a diamond mesh from a tspline. However it seems that not all faces of the tspline are oriented in the same direction ( and in a later stage of the design I need them to be). The image shows the numbering of the edges. As you can see the ones with yellow circles are different. This is just a small part of the whole mesh. How can I get the faces to face the same direction? The mesh normals are fine btw. Hope there is some easy component to fix this. Thanks. 

Esther