I would go with one Shael rune, and use a rune over the perfect topaz, as suggested above. BcBecause Orr runes give 1-50 lightning, as opposed to 1-40 from the perfect topaz. I would also suggest a Thul rune for 3-14 cold damage or a Ral rune for 5-30 fire damage.
I recommend the runes because a quick countess run in nightmare will give you these runes quite often, and perfect gems are harder to come by.