Quality and workmanship are accustomed WMF good workmanship. Very valuable, sits comfortably in the hand and on the table. On the bottom of the cup a discreet WMF logo.
The egg cups can be washed in the dishwasher.
Let us subject to the "main" of the reviews of this product: stackable or not?
The cup grip due to the design not complete each other when you stack them. This may result in camera shake and instability. However, if you stay the parts above the other sets neatly in the closet etc. these are also without falling over, slipping etc.
I uploaded here a photo that illustrates the fact.
Here the manufacturer has not promised too much so well.
But it all comes down primarily to the function as egg cups ... and there is nothing in the product suspended. Because of the processing, we will probably need no other egg cups more for many years.