To get +2 skill in amulet, you need alvl90 (affix level 90)
To get alvl90 in an amulet you need ilvl90 (item level 90)
The ilvl on a craft is half the ilvl of the item you use as the base and half of your character level, both rounded down.
If you gamble an amulet with a clvl93 the lowest the ilvl of the amulet is going to be is ilvl88 (since gamble is your level -5+4), so if you craft with the same character and that amulet
you get 44 ilvls from the amulet and 46 from your character for a total of ilvl90, enough to get +2 skills (could be higher if the gambled amulet has higher ilvl, but never lower)
With TZ is the same, if you are in a T91 the amulets are going to be at least ilvl93, if you gamble with a lvl91 char then the craft will be at least ilvl91, you don't even need lvl91, you can do it also at lvl90.
Thanks man, very helpful comment. I sent you a tip, cheers.