3 chipped gems
+ 1 sword (any)
=
Magical sword of the same type with new, random mods and 3 sockets
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The sword will become magical, with 3 sockets. Cruel is only possible with 6 elite swords, Conquest, Cryptic, Mythical, Champion, Col Sword, Col Blade.

Just in case you decide to try and craft yourself a cruel balrog blade this will save you time on the swords you can get to be cruel with the 3 CGC method of rolling items.