Not sure what you mean.
If you mean how to you add sockets to it - either complete the A5 Larzuk Quest (Always 4 sockets) or put it in your cube with Tal + Thul + Perfect Topaz (This will give you a random number of sockets)
If you mean what to socket it with - An eth AP suggests you probably want to make a merc armor - best choices are Fortitude (El+Sol+Dol+Lo) (4 Sockets) or Treachery (Shael+Thul+Lem) (3 Sockets)