gems.txt  Final version 2 for NetHack 3.2.2
Compiled by Kevin Hugo <hugo@cae.wisc.edu>.
Quoted in part by Jonathan Ellis for NetHack 3.2.3.
(The "luck" part of the spoilers has been removed to a separate file.)

GEMS AND STONES           COST  WGT  PROB   ENGR  COLORS
~~~~~~~~~~~~~~~~~~~~~~~ : ~~~~  ~~~  ~~~~ : ~~~~  ~~~~~~
Valuable gems           :                 :
  dilithium crystal     :$4500    1    3  : soft  white
  diamond               : 4000    1    4  : hard  white
  ruby                  : 3500    1    5  : hard  red
  sapphire              : 3000    1    6  : hard  blue
  emerald               : 2500    1    7  : hard  green
  turquoise             : 2000    1    8  : soft  green, blue
  aquamarine            : 1500    1   10  : hard  green, blue
  amber                 : 1000    1   11  : soft  yellowish brown
  topaz                 :  900    1   13  : hard  yellowish brown
  opal                  :  800    1   15  : soft  white
  garnet                :  700    1   17  : soft  red
  amethyst              :  600    1   19  : soft  violet
  jasper                :  500    1   21  : soft  red
  fluorite              :  400    1   22  : soft  green, blue, white, violet
  jade                  :  300    1   23  : soft  green
Worthless gems          :                 :
  blue glass            :    0    1  113  : soft  blue
  green glass           :    0    1  113  : soft  green
  red glass             :    0    1  113  : soft  red
  violet glass          :    0    1  113  : soft  violet
  white glass           :    0    1  113  : soft  white
  yellowish brown glass :    0    1  113  : soft  yellowish brown
Other stones            :                 :
  luckstone             :   60   10   10  : soft  gray stone
  flintstone            :    1   10   18  : soft  gray stone
  loadstone             :    1  500   10  : soft  gray stone
  rock                  :    0   10  100  : soft  rock

Gems and stones are listed above by category, then by decreasing price.
The COST field denotes the base price of each item.  WGT specifies the
weight (100 zorkmids weighs 1).

Gems comprise 8% of all randomly-generated items in the main dungeon,
18% in containers, 0% in Roguelike bones piles, and 10% in hell.  PROB is
the relative probability of each subtype.  Loadstones are always cursed,
all others apart from luckstones are uncursed.  (If you uncurse a loadstone 
so you can drop it, it will become cursed again the moment you have dropped 
it...) Rocks appear in piles of 6 to 11.  Valuable gems, worthless gems, and 
flintstones have a 1/6 chance of appearing in a pile of 2.

The ENGR field denotes how the gem appears when you attempt to #engrave
with it (see below).  COLORS specifies the possible apearance of the gem.
If more than one color is possible, then one will be randomly chosen for
the appearance.


Identifying gems
~~~~~~~~~~~~~~~~
(Quoted in part from the spoiler "gems" by Bryan Butler
<butler@cluster.gps.caltech.edu>.)

There are now six methods to identify gems: engraving, throwing at
unicorns, collecting a large number, scrolls or spells of identify,
dipping an amethyst in potions of booze, and finding pre-placed gems.
The method formerly known as "kickboxing" no longer works in Nethack 3.2.

1.  Engraving with gems

If a gem is listed as "hard" above, then you will see the following
message when you attempt to (E)ngrave with the gem:
    "You engrave in the floor with the <gem>."
where <gem> is the appearance of the gem.  All hard gems are valuable,
although some colors may have more than one possible identity.

If the gem is "soft," you will see this message:
    "You write in the dust with the <gem>."
Soft gems may be valuable or worthless, so you will need an additional
method to identify these gems.

In either case, you can abort the engraving process by pressing Escape.
If you choose to write a message, it will take one turn per character
to engrave.  Not all types of floor can be engraved upon.  You may choose
to #name a gem once you know its hardness (e.g., "soft blue").

Note the following:
hard white gems are *always* diamonds
hard red gems are *always* rubies
hard yellowish brown gems are *always* topaz
hard blue gems may be sapphires or aquamarines
hard green gems may be emeralds or aquamarines

soft yellowish brown gems are either amber or glass
soft red gems are garnets, jasper or glass
soft violet gems are amethyst, fluorite or glass
soft white gems are dilithium, opal, fluorite or glass
soft green gems are jade, turquoise, fluorite or glass
soft blue gems are turquoise, fluorite or glass

2.  Throwing gems at unicorns

Throwing a gem to a unicorn can change your luck in one of several
ways, depending on whether the gem is worthless or valuable, whether you
are the same alignment as the unicorn (white = lawful, gray = neutral,
and black = chaotic), and whether the gem type is already identified or
named.

  VALUE  ALIGN  KNOWN       ADVERB        LUCK CHANGE
  ~~~~~  ~~~~~  ~~~~~~~~~~  ~~~~~~~~~~~~  ~~~~~~~~~~~
  glass  other  unknown     graciously         0
  glass  other  named       (see below*)       0
  glass  other  identified  (see below*)       0
  glass  same   unknown     graciously         0
  glass  same   named       (see below*)       0
  glass  same   identified  (see below*)       0
   gem   other  unknown     hesitatingly   -1 to +1
   gem   other  named       hesitatingly   -1 to +1
   gem   other  identified  hesitatingly   -3 to +3
   gem   same   unknown     gratefully        +1
   gem   same   named       gratefully        +2
   gem   same   identified  gratefully        +5

In most cases, the message sequence is as follows:
    "The <unicorn> neighs!  The <unicorn> catches the <gem>."
    "The <unicorn> <ADVERB> accepts your gift."
where the color of the unicorn and the color of the gem are appropriate
for the situation. <ADVERB> comes from the table above, except where
the column has a *, in which case there is a different message sequence:
    "The <unicorn> neighs!"
    "The <unicorn> catches the <glass>."
    "The <unicorn> is not interested in your junk."
after which the unicorn will promptly drop the "gem".

3.  Collecting a large number of gems

If you wait long enough, you'll accumulate a large number of gems.
Since the probabilities of getting worthless pieces of glass are so
much higher than getting true gems, you'll acquire them much faster
than other gems. So, if you just wait long enough, and look at all of
the gems of a certain color that you have, more often than not the gem
of which you have the most is the worthless piece of glass. This is a
bit risky, and usually takes much more time than other methods.

4.  Scrolls and spells of identify

You can always use a scroll or spell of identify to determine whether a
gem is valuable.  You will then recognize all gems of that same type,
although you can lose this knowledge from a scroll of amnesia or mind
flayer attack.  Archeologists always begin with all gems (but not stones)
identified in this manner.  Shopkeepers will buy identified gems based on
their full price; this is a good way to get money.

5.  Dipping amethysts into potions of booze

When you dip an amethyst into a potion(s) of booze, the potion will turn
into fruit juice ("a-methyst" means not intoxicated).  You can use this
very special case to identify this type of soft violet gems.

6.  Pre-placed gems

Certain levels are guaranteed to be generated with diamonds, rubies,
emeralds, and amethysts in well-defined positions.  Both versions of the
bottom level of the Gnomish Mines contain a room with these four types of
gems, a guaranteed luckstone, and other random gems.  The four courner
rooms of Fort Ludios (if it exists in your game) each contain one of
these four types of valuable gems.  Other levels may also be generated
with piles of gems, but their type is not guaranteed, so these levels are
not helpful in determining the identity of gems.
