Thanks Bernard C! It is a very "traditional" thing to consider 6 a "complete" set. Either way i'm happy but i guess it was just curiosity.
Ironicly i bought a set like this in pink design (which came with 6 glasses) and 2 glasses smashed on delivery, so at least both of my sets will be the same

And these will be for display and not necessarily for actual use! Cos they are too nice i think