Well, if they really are ANDs, then you'll need to break them down as such.
<ItemRule itemBaseType="Armor" description="Keep Armor">
<StatRules>
<Rule stat="Dexterity" minValue="100" quality="Rare4"/>
</StatRules>
</Itemrule>
<ItemRule itemBaseType="Armor"...
Just break them out into different item rules.
<ItemRule itemBaseType="Jewelry" description="Keep Armor">
<StatRules>
<!-- All Armor with min value of 100 Dex.-->
<Rule stat="Dexterity" minValue="100" quality="Magic1" />
<Rule stat="Dexterity" minValue="100"...
I believe if you stick all of those Rule stats in the same StatRules block, it will only match Magic1 items with dex, int, GF, MF, AS, crit dmg, crit, and resist all. Same with Rare4 items.