Thinking diamonds? Or a some jewels?
Hmmm. Would have to know more detail.
Jewels and more specifically rare jewels. Ones with enhanced defence.
Depends on what you are trying to do with the character.
Make a duress runeword in 3 socket armour if ur melee class
Aha you fell for the same trap I jumped over.
It’s magic armor. 
Thank you. Yeah, pretty low level character. I played this when it was new back in the day. I am running a Paladin, right now hammers and melee. I have a magic full plate for me with 3 sockets, and an ethereal 4 socket normal for my companion I think “fortitude” for the merc?
Kind of an expensive rune set for a merc. Then again I don’t know if you have lots of runes.
For non-magic find stuff I put rare armors I won’t use on the merc. The more armor rating the better. Using an Act 2 merc with Strength rune word polearm is a solid choice.
Poke, Poke!