Alter Aeon Online Help

Keywords are:  'necromancer soulstones soulgems stones'

Soulstones are the currency of life for necromancers.  When a creature
is near death, a soulstone may be created by trapping the spirit of
the creature inside a gem.  The 'soulsteal' necromancer spell is used
for this purpose.

Soulstones are used when raising undead, and are also used as bargaining
chips when dealing with demons.  Most transactions with a demon will
involve a soulstone, no matter how minor.

Soulstones come in different grades and power levels, denoted by the
color of the stone:

Color            Level   Use
------------------------------------------
red             0 -  9   Demon familiar
yellow         10 - 15   Demonic detect
green          16 - 23   Demon identify
cyan/pale blue 24 - 33   Demon lockinfo, demonic protect
blue           34 - 46   Shadow fiend, demon spell components
purple         47 - 59   Bone dragon, demon alchemist, teeth
clear          60 - 72   Demon magic power
white          73 - 85   Demonic tutor
black          86+       Demonic wardbreaker, enchanting

If you need a soulstone in a hurry, you may be able to buy one from
the soulstone market using the 'soulmarket' command.