star transfers work like this

1-7 lose 1
8 -9 lose 2
10-17 lose 1
18 lose 0
several people have posted the 18 star info in the past. I have not done one yet so i personally can not verify. but all the info from 1-15 is straight from ucool in a message they sent me on a support ticket when the transfer option was first release. At that time we could only go to 15 stars.