I guess they will never make a patch with +12.
I mean just look the prices:
1 DB = 215 CPs.
Not Buyable:
+1 Stone = 12 CPs = 0,05 DBs
+2 Stone = 36 CPs = 0,16 DBs
Buyable:
+3 Stone = 108 CPs = 0,5 DBs
+4 Stone = 324 CPs = 1,5 DBs
+5 Stone = 972 CPs = 4,5 DBs
+6 Stone = 2916 CPs = 13 Dbs
Not Existing:
+7 Stone = 8748 CPs = 40,68 DBs
+8 Stone = 26244 CPs = 122 DBs
+9 Stone = 78732 CPs = 366 DBs
Now... Imagine someone would try to make a +10 item...
And to buy or win a +8 item in lottory would be much cheaper then buying that stones!