FICO gaurds their scoring formulae very carefully, which compromises efforts to answer this question accurately. However, there are a few factors that "super-prime" scores tend to have in common:

-A long credit history (preferably 30 years more).
-A long average age of credit accounts (more older accounts, fewer new ones).
-No "derogatories" (late payments, chargoffs, judgements, etc.)
-Very low "utilization" of available credit
-Few or no recent applications for new credit (particularly revolving credit, like credit cards)
-Only prime credit: bank credit cards, mortgages, etc., rather than consumer finance companies or secured credit cards
-A good "mix" of credit: for example, perhaps a mortgage, a couple of student loans, a single store or gas card, and a couple of prime bank cards

If your report shows all these elements, the 800 range is very likely. If they're all perfect (and they never quite are), than approaching an 850 becomes possible.