how to craft dual leech ring

http://forum.europebattle.net/threads/crafting-handbook.541278/

(S) "of the Lamprey" (level 77, levelreq 65, group 27): 7-8 % Life Stolen Per Hit
(S) "of the Vampire" (level 86, levelreq 74, group 28): 6 % Mana Stolen Per Hit

Optimised Crafting
Rings have qlvl 1, just like Amulets. Thus, we need at least Ilvl 77 and at most Ilvl 85,

That is, Whenever rlvl 96 is of any concern, use a level 80-83 character to gamble and craft Rings.
Conversely, if we want every Ring to have a chance of acquiring 6 % Mana Stolen Per Hit, we should use a character of at least level 89, in which case we might occasionally be looking at rlvl 96. If we use a level 80-83 character to gamble and craft, then at most rlvl 88.

So if you want chance of highest mana leech then crafting with lvl 91 char is ok.
But you need to gamble the rings use a lvl 80-83 char.
And only use blue rings with item lvl 77 to 85.