Use the runed stone again as soon as you enter this
level.  More green runes should appear on the walls.
Follow the runes through the first network of 
tunnels to avoid the blades traps.  At the first
intersection near (13,50) head east, then turn to
the northwest through intersections near (18,46), 
and north at (17,44).  There is a secret passage on
the rune at (17,38), where you can restore health
and spell points.  Then continue east into the next
chambers.

Head straight east and step on (35,36), and some 
gems will spill on the floor.  Pick them up, 
because you cannot pass the tunnel to the north at
(35,35) until the gems have been placed on the 
proper pedastals.  

There are three chambers connected to this passage, 
and in the middle of each are clues as to the order 
of the gems.  Two pedastals in each room have runes 
behind them:  it is on top of these pedastals that 
the gems must be placed.

Gem locations from left to right:

ruby or emerald at (31,43)
emerald or ruby at (33,43)
ruby at (41,42)
diamond at (41,40)
diamond at (43,36)
emerald at (45,34)

Go through the passage and follow the runes to the west.

The passage east is a long but direct journey to the 
altar where a certain sword was forged.  Do not go this
way unless you have the sword and have prayed at least
two of the "special" hidden altars. There is one of these
altars hidden behind a secret passage on a rune at (36,27).  

The passage winds around, and there is a secret door that
leads to a shortcut around the gazers at (23,19).  Kill
the two groups of Drakes you encounter, then leave the 
level through a secret passage at (6,54), which is at the
end of the cave of the second group of Drakes.