Yes, Onion skins "onions" (shown in the 2 pix I posted) are Antique German cane cut marbles, as are all the "glass" Germans (Antique Cane cut) present in your photos. "If" you have any Lutz or aventurine present in any of your german handmades, yes it is desirable. From the pix I can't tell if you do or don't. Condition is always # 1 in marbles as far as value goes ( machine made, handmade or contemporary) I remember when I started collecting, my mentor telling me, condition, condition, condition. There are a few cases where you can have an extremely rare marble and it will still have value but the other 98% as far as value is all condition. I always collect what I like and get the best example possible, the only one you have to make happy is you ..
Here is a picture of an onionskin I have loaded w/ lutz, they are a very beautiful marble IMO, the high mint condition makes a big difference in both appearance (clarity) and value.