100% accurate
Quote (http://classic.battle.net/diablo2exp/items/magic/pre.shtml)
Ruby Fire Resist +31-40% Amulets(25), Armor(25), Boots(25), Circlets(25), Orbs(25), Rings(25)
Quote (http://classic.battle.net/diablo2exp/items/cube.shtml)
1 Tal Rune + 1 Amn Rune + 1 Perfect Ruby + Normal Shield = Socketed Shield of same type
The item gets 1-4 sockets, randomly. However, the number of sockets is then restricted by the maximum number of sockets that base item with that ilvl can have. For example, if you have an item that can only have 2 sockets, there's a 3/4 chance of getting 2 sockets and a 1/4 chance of getting 1 socket.