It is found in Mdina as well as MDG. Pieces executed just like this were made in both places.
When it comes to Earthtones, you need labels or other indicators to tell where it was made, to be sure.
Currently, we strongly suspect that the faint "batutto-like" grooves found on some polished bases are an indicator of MDG. That is what the current evidence leads to, but we do not know for sure, not 100% proof positive.