# Gem

Item classes

"&nbsp;Amulets

[&nbsp;Armor

%&nbsp;Comestibles

$&nbsp;Coins

*&nbsp;Gems

!&nbsp;Potions

=&nbsp;Rings

?&nbsp;Scrolls

+&nbsp;Spellbooks

`&nbsp;Statues

(&nbsp;Tools

`&nbsp;Boulders

)&nbsp;Weapons

/&nbsp;Wands

For the material, see gemstone.
In NetHack, gems are simple and typically lightweight items found in the dungeon. They come in three varieties: valuable gems, worthless pieces of glass which look similar, and gray stones. Another type of item that uses the same glyph is the rock, which is handled differently.
Valuable identified gems may be sold for relatively large amounts of money at most general stores, which makes them valuable as a compact form of money. However, shopkeepers will always buy unidentified gems as if they are worthless glass, and will always sell unidentified gems as if they are valuable, possibly subject to a further 33% surcharge for being unidentified. Valuable gems may also be thrown to a co-aligned unicorn to get a large Luck increase. Throwing any valuable or worthless gem to a unicorn will pacify them, and will variably raise or lower luck in certain cases. See the unicorn page for details. Valuable gems also give score, but as score does not normally matter, this is typically of low importance.
Glass and rocks are relatively worthless, though they can be used for throwing if you should wish to conserve your other attacks. Additionally, they can occasionally be polymorphed into more valuable gems if included in a polypile, though it's not worth wasting a wand charge on them. Rocks can also be changed in to meatballs, useful for taming and for sale in shops.
Despite the name, a worthless piece of 

<color> glass will not shatter like other glass items if thrown against a wall or dropped while levitating. You can fire them from slings as a lighter version of rocks; like rocks, they can be multishot. If they are used as ammo however, both worthless pieces of glass and precious gems may disappear (like arrows).

Contents

1 Tables of gems

1.1 By value
1.2 By color

2 Generation and identification
3 Prices when unidentified
4 Gray stones
5 SLASH'EM

5.1 Alchemy with gems

6 Encyclopedia entries

6.1 Gem or rock
6.2 Agate
6.3 Amber
6.4 Diamond
6.5 Dilithium
6.6 Emerald
6.7 Jacinth stone
6.8 Jade
6.9 Obsidian
6.10 Ruby and sapphire
6.11 Topaz stone
6.12 Turquoise stone

Tables of gems
By value
Some gems' appearances can change. In these cases all the options are listed. The actual appearance is randomly chosen from the options at the beginning of each new game, and is consistent throughout that game (if one fluorite is white, all fluorites in that game will be white). The hardness of a gem can be tested by #engraving with it; if the gem is hard, the game will prompt "What do you want to engrave?"; if it is soft, "What do you want to write in the dust?"

*

Name

Description

Cost&nbsp;(zm)

Weight

Hardness

Prob (‰)

Material

*

dilithium crystal

white gem

4500

1

soft

2

gemstone

*

diamond

white gem

4000

1

HARD

3

gemstone

*

ruby

red gem

3500

1

HARD

4

gemstone

*

jacinth stone

orange gem

3250

1

HARD

3

gemstone

*

sapphire

blue gem

3000

1

HARD

4

gemstone

*

black opal

black gem

2500

1

HARD

3

gemstone

*

emerald

green gem

2500

1

HARD

5

gemstone

**

turquoise stone

green gemblue gem

2000

1

soft

6

gemstone

*

citrine stone

yellow gem

1500

1

soft

4

gemstone

**

aquamarine stone

green gemblue gem

1500

1

HARD

6

gemstone

*

amber stone

yellowish&nbsp;brown&nbsp;gem

1000

1

soft

8

gemstone

*

topaz stone

yellowish&nbsp;brown&nbsp;gem

900

1

HARD

10

gemstone

*

jet stone

black gem

850

1

soft

6

gemstone

*

opal

white gem

800

1

soft

12

gemstone

*

chrysoberyl stone

yellow gem

700

1

soft

8

gemstone

*

garnet stone

red gem

700

1

soft

12

gemstone

*

amethyst stone

violet gem

600

1

soft

14

gemstone

*

jasper stone

red gem

500

1

soft

15

gemstone

****

fluorite stone

green gemblue gemwhite gemviolet gem

400

1

soft

15

gemstone

*

jade stone

green gem

300

1

soft

10

gemstone

*

obsidian stone

black gem

200

1

soft

9

gemstone

*

agate stone

orange gem

200

1

soft

12

gemstone

*

worthless piece of white glass

white gem

0

1

soft

77

glass

*

worthless piece of blue glass

blue gem

0

1

soft

77

glass

*

worthless piece of red glass

red gem

0

1

soft

77

glass

*

worthless piece of yellowish brown glass

yellowish&nbsp;brown&nbsp;gem

0

1

soft

77

glass

*

worthless piece of orange glass

orange gem

0

1

soft

76

glass

*

worthless piece of yellow glass

yellow gem

0

1

soft

77

glass

*

worthless piece of black glass

black gem

0

1

soft

76

glass

*

worthless piece of green glass

green gem

0

1

soft

77

glass

*

worthless piece of violet glass

violet gem

0

1

soft

77

glass

*

luckstone

gray stone

60

10

soft

10

mineral

*

loadstone

gray stone

1

500

soft

10

mineral

*

touchstone

gray stone

45

10

soft

8

mineral

*

flint stone

gray stone

1

10

soft

10

mineral

*

rock

rock

0

10

soft

100

mineral

By color
The gems that have a randomized appearance are marked with an asterisk, "*".

A user has suggested improving this page or section as follows:
"The unidentified sell price column hasn't been updated since 3.4.3 and is out of date, and probably nobody cares enough to update it, because the prices are a huge pain to calculate."

Color

Possibilities

Cost

Unidentified sell price

Level

Hardness

0

1

2

*White

dilithium crystal

4500

4

4

6

27

soft

diamond

4000

5

5

3

24

HARD

opal

800

5

7

3

1

soft

fluorite stone*

400

4

7

4

1

soft

worthless glass

0

8

6

4

1

soft

*Blue

sapphire

3000

8

3

6

15

HARD

turquoise stone*

2000

5

6

5

6

soft

aquamarine stone*

1500

7

3

3

1

HARD

fluorite stone*

400

4

7

4

1

soft

worthless glass

0

3

7

5

1

soft

*Red

ruby

3500

6

6

4

21

HARD

garnet stone

700

7

4

5

1

soft

jasper stone

500

3

6

3

1

soft

worthless glass

0

4

3

6

1

soft

*Yellowish brown

amber stone

1000

8

4

4

1

soft

topaz stone

900

3

5

5

1

HARD

worthless glass

0

5

4

3

1

soft

*Orange

jacinth stone

3250

7

7

5

18

HARD

agate stone

200

6

4

6

1

soft

worthless glass

0

6

5

4

1

soft

*Yellow

citrine stone

1500

6

7

6

3

soft

chrysoberyl stone

700

6

3

4

1

soft

worthless glass

0

7

6

5

1

soft

*Black

black opal

2500

3

4

3

12

HARD

jet stone

850

4

6

6

1

soft

obsidian stone

200

5

3

5

1

soft

worthless glass

0

8

7

6

1

soft

*Green

emerald

2500

4

5

4

9

HARD

aquamarine stone*

1500

7

3

3

1

HARD

jade stone

300

7

5

3

1

soft

fluorite stone*

400

4

7

4

1

soft

turquoise stone*

2000

5

6

5

6

soft

worthless glass

0

3

3

3

1

soft

*Violet

amethyst stone

600

8

5

6

1

soft

fluorite stone*

400

4

7

4

1

soft

worthless glass

0

4

4

4

1

soft

Generation and identification
To be formally identified means that a gem can be sold at a shop using its base price instead of just a few zorkmids; even if you've found all the other members of the white gem family, including the worthless glass bauble, the shopkeeper will not take "a white gem called diamond" at face value.  Much like other forms of identification, gems can be formally identified by:

scrolls or spells of identification, the former of which is generally considered wasteful to use on gems unless it is blessed to begin with
Sitting on thrones and hoping for a blessed identification
Using a touchstone, which must be blessed to perform formal identification for everyone except gnomes and archeologists (who only require it to be uncursed).
Before all that, there are easy ways of determining which gems are worth the effort of formally identifying.
Some valuable gems can only be generated at specific dungeon levels or below. If a particular valuable gem would have been created but the dungeon level is not deep enough, a different valuable gem will be generated instead.  Dungeon level does not otherwise affect gem probability, and the ratio of randomly generated gems to randomly generated glass is roughly 1:4 regardless of dungeon level.
These are the minimum levels for certain valuable gems:

Dungeon level

Gem

3
citrine stone

6
turquoise stone

9
emerald

12
black opal

15
sapphire

18
jacinth stone

21
ruby

24
diamond

27
dilithium crystal

Any other gems not listed above can be generated on any dungeon level.
Additionally, there are places where certain types of gems are guaranteed to be generated. Twelve gems – three diamonds (white), three emeralds (green), three rubies (red), and three amethysts (violet) – are guaranteed in the corner turrets of Fort Ludios, for example. Also, each bottom of the Gnomish Mines has several guaranteed gems, including at least an uncursed luckstone and an amethyst.
Amethysts have the special property of converting booze into fruit juice, which may be used to informally identify them (and also booze and fruit juice).
An uncursed touchstone can easily separate glass from valuable gems. Even without one, there are ways of distinguishing valuable gems from glass. Some players type-name all gems to take advantage of the fact the hardness/color/price/is-glass quadruple is unique for each type of gem. The inventory list automatically creates stacks of different unidentified gems that are described as the same color; there is only one pile of worthless glass of any given color. Next is hardness – all hard gems are valuable – and hardness can easily be tested by trying to engrave with gems on the dungeon floor. If you engrave in the dust, the gem is soft; if you scratch the floor itself, the gem is hard. Of the remaining groups of soft gems, you can throw one of each stack at a cross-aligned unicorn while utilizing naming tricks to keep track of which gems were found, which gems were to be thrown at the unicorn, and which gems were rejected by the unicorn. Cross-aligned unicorns only accept valuable gems "hesitatingly" and there is no Luck penalty for killing them, if without a Pet, though there may be an unknown Luck adjustment when they catch said valuable gems.
Do not bother to BUC identify your gems (not counting gray stones) at an altar. They are always generated uncursed and their BUC status has no effect. Marking them uncursed at an altar just causes the gems to fail to stack when you pick up more gems of the same type that haven't been formally BUC identified, wasting inventory slots. This can be particularly annoying if you are distinguishing valuable gems without formally identifying them, e.g. by throwing them at unicorns or using an uncursed touchstone, as it will prevent gems you pick up from stacking with named stacks.

Prices when unidentified
When selling gems which have not been formally identified to a shop, you will be offered a price from one of the "Unidentified sell price" columns. The values here will sometimes allow you to identify the gem. The column used is fixed for each shop (but may differ between shops), which may allow more gems to be identified if the column can first be determined.
The price table depends on compile time options. If you compiled NetHack yourself, check it is still valid.

Gray stones
A gray stone can be one of the following items:

Touchstones may be used to identify glass from gems, and even the variety of gem if it is a blessed touchstone or you are a gnome or archeologist.
Luckstones will augment your luck rather impressively; if you have a blessed luckstone and no other luck items, your good Luck will not timeout, bad Luck will, and you'll get +3 extra Luck.
Loadstones are a pun (dating back to early editions of Dungeons and Dragons): at 500 weight units, they weigh 50 times as much as the other gray stones, and they autocurse (and are generated cursed) so they cannot be dropped.
Flint stones have no particular purpose, but they do slightly better as sling ammo.
Unlike other gems, unidentified gray stones are priced by shopkeepers at their normal values, so price identification is a viable way to identify them.

SLASH'EM
Due to the existence of migohives, identifying four gems is slightly easier in SLASH'EM, because only these gems are generated in migohives: diamonds, rubies, agate stones, and fluorite stones. Hence, if you find a white gem in a migohive and can engrave with it, it's a diamond, and otherwise it's a fluorite stone. Blue, green, or purple gems found in migohives are also fluorite stones. If you find a red gem in a migohive, it's a ruby, and if you find an orange gem, it's an agate stone.

Alchemy with gems
Valuable gems can be dipped into a potion of acid to make new potions. See Alchemy §&nbsp;Gem alchemy for details.

Encyclopedia entries
Gem or rock

The difference between false memories and true ones is the same as for jewels:  it is always the false ones that look the most real, the most brilliant.

[ Salvador Dali ] 

Agate

Translucent, cryptocrystalline variety of quartz and a subvariety of chalcedony.  Agates are identical in chemical structure to jasper, flint, chert, petrified wood, and tiger's-eye, and are often found in association with opal.  The colorful, banded rocks are used as a semiprecious gemstone and in the manufacture of grinding equipment.  An agate's banding forms as silica from solution is slowly deposited into cavities and veins in older rock.

[ The Columbia Encyclopedia, Sixth Edition ] 

Amber

"Tree sap," Wu explained, "often flows over insects and traps them.  The insects are then perfectly preserved within the fossil.  One finds all kinds of insects in amber - including biting insects that have sucked blood from larger animals."

[ Jurassic Park, by Michael Crichton ] 

Diamond

The hardest known mineral (with a hardness of 10 on Mohs' scale). It is an allotropic form of pure carbon that has crystallized in the cubic system, usually as octahedra or cubes, under great pressure.

[ A Concise Dictionary of Physics ]
The diamond, _adamas_ or _dyamas_, is a transparent stone, like crystal, but having the colour of polished iron, but it cannot be destroyed by iron, fire or any other means, unless it is placed in the hot blood of a goat; with sharp pieces of diamond other stones are engraved and polished.  It is no greater than a small nut.  There are six kinds, however Adamant attracts metal; it expels venom; it produces amber (and is efficacious against empty fears and for those resisting spells).  It is found in India, in Greece and in Cyprus, where magicians make use of it.  It gives you courage; it averts apparitions; it removes anger and quarrels; it heals the mad; it defends you from your enemies.  It should be set in gold or silver and worn on the left arm.  It is likewise found in Arabia.

[ The Aberdeen Bestiary, translated by Colin McLaren ]
 

Dilithium

The most famous and the first to be named of the imaginary "minerals" of Star Trek is dilithium. ... Because of this mineral's central role in the storyline, a whole mythology surrounds it.  It is, however, a naturally occurring substance within the mythology, as there are various episodes that make reference to the mining of dilithium deposits.... This name itself is imaginary and gives no real information on the structure or make-up of this substance other than that this version of the name implies a lithium and iron-bearing aluminosilicate of some sort.  That said, the real mineral that most closely matches the descriptive elements of this name is ferroholmquistite which is a dilithium triferrodiallosilicate. If one goes on the premise that nature follows certain general norms, then one could extrapolate that dilithium might have a similar number of silicon atoms in its structure.
Keeping seven (i.e. hepto) ferrous irons and balancing the oxygens would give a theoretical formula of Li2Fe7Al2Si8O27. A mineral with this composition could theoretically exist, although it is doubtful that it would possess the more fantastic properties ascribed to dilithium.

[ The Mineralogy of Star Trek, by Jeffrey de Fourestier ] 

Emerald

'Put off that mask of burning gold
With emerald eyes.'
'O no, my dear, you make so bold
To find if hearts be wild and wise,
And yet not cold.'

'I would but find what's there to find,
Love or deceit.'
'It was the mask engaged your mind,
And after set your heart to beat,
Not what's behind.'

'But lest you are my enemy,
I must enquire.'
'O no, my dear, let all that be;
What matter, so there is but fire
In you, in me?'

[ The Mask, by W.B. Yeats ] 

Jacinth stone

Sweet in the rough weather
&nbsp;&nbsp;The voice of the turtle-dove-
'Beautiful altogether
&nbsp;&nbsp;Is my Love.
&nbsp;&nbsp;His Hands are open spread for love
And full of jacinth stones-
&nbsp;&nbsp;As the apple-tree among trees of the grove
Is He among the sons.'

[ The Beloved, by May Probyn ] 

Jade

Nothing grew among the ruins of the city.  The streets were broken and the walls of the houses had fallen, but there were no weeds flowering in the cracks and it seemed that the city had but recently been brought down by an earthquake.  Only one thing still stood intact, towering over the ruins.  It was a gigantic statue of white, gray and green jade - the statue of a naked youth with a face of almost feminine beauty that turned sightless eyes toward the north.
"The eyes!" Duke Avan Astran said.  "They're gone!"

[ The Jade Man's Eyes, by Michael Moorcock ] 

Obsidian

A volcanic glass, homogeneous in texture and having a low water content, with a vitreous luster and a conchoidal fracture.  The color is commonly black, but may be some shade of red or brown, and cut sections sometimes appear to be green.  Like other volcanic glasses, obsidian is a lava that has cooled too quickly for the contained minerals to crystallize.  In chemical composition it is rich in silica and similar to granite. It is favored by primitive peoples for knives, arrowheads, spearheads, and other weapons and tools.

[ The Columbia Encyclopedia, Sixth Edition ] 

Ruby and sapphire

_Corundum._ Mineral, aluminum oxide, Al2O3.  The clear varieties are used as gems and the opaque as abrasive materials.  Corundum occurs in crystals of the hexagonal system and in masses.  It is transparent to opaque and has a vitreous to adamantine luster. [...] The chief corundum gems are the ruby (red) and the sapphire (blue).

[ The Columbia Encyclopedia, Sixth Edition ] 

Topaz stone

Aluminum silicate mineral with either hydroxyl radicals or fluorine, Al2SiO4(F,OH)2, used as a gem.  It is commonly colorless or some shade of pale yellow to wine-yellow; [...] The stone is transparent with a vitreous luster.  It has perfect cleavage on the basal pinacoid, but it is nevertheless hard and durable.  The brilliant cut is commonly used.  Topaz crystals, which are of the orthorhombic system, occur in highly acid igneous rocks, e.g., granites and rhyolites, and in metamorphic rocks, e.g., gneisses and schists.

[ The Columbia Encyclopedia, Sixth Edition ] 

Turquoise stone

TUBAL: There came divers of Antonio's creditors in my company to Venice that swear he cannot choose but break.
SHYLOCK: I am very glad of it; I'll plague him, I'll torture  him; I am glad of it.
TUBAL: One of them showed me a ring that he had of your daughter for a monkey. 
SHYLOCK: Out upon her!  Thou torturest me, Tubal.  It was my turquoise; I had it of Leah when I was a bachelor; I would not have given it for a wilderness of monkeys.

[ The Merchant of Venice, by William Shakespeare ] 

This page may need to be updated for the current version of NetHack.
It may contain text specific to NetHack 3.4.3. Information on this page may be out of date.
Editors: After reviewing this page and making necessary edits, please change the {{nethack-343}} tag to the current version's tag or {{noversion}} as appropriate.

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