Here's my lvl 7 dwarf AC breakdown (sorry he was 52 not 53AC)
10 base
5 dex bonus (20dex) with mithral full plate and dwarf and fighter armor mastery enhancements
12 +4 mithral full plate
8 +4 mithral tower shield
3 +3 natural armor bonus (crafted necklace)
4 +4 protection cloak (crafted)
2 +2 dodge (stalwart defender stance)
5 combat expertise
1 dodge feat
1 stalwart defender enhancement
1 natural AC bonus from airship
52
he has DR 2/- and the 20% resistance to physical damage from shield mastery just in case anyone hits him
He's just levelled to 8 now and has gained another AC from +5 shield, and will get another when I get +5 armor.
I just realise I can sneak another one easily with a crafted +1 dodge item.
[EDIT] He's just got the world's most horrible +5 mithral full plate and a crafted dodge item to get AC55 at lvl8 all with easily obtainable gear.
No ioun stone alas!