Crystal plate mail

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[   crystal plate mail   Crystal plate mail.png
Appearance crystal plate mail
Slot body armor
AC 7
Base price 820 zm
Weight 450
Material glass

Crystal plate mail is a type of armor that appears in NetHack. It is made of glass.


In addition to random generation, general stores and armor shops can stock crystal plate mail.

A set of crystal plate mail is always generated in one of the niches on the middle floor of Vlad's Tower.

Mercenaries with a target AC of -1 or better (e.g., Yendorian Army lieutenants) have an effective 425 chance of generating with crystal plate mail.[1]

Player monster barbarians, knights, priests, and valkyries have an effective 162 chance (roughly ~1.61%) of forcing crystal plate mail in place of their initial body armor.[2][3][4][5]


While worn, crystal plate mail provides 7 base AC and MC2, similar to plate mail. As armor made of glass, it is fragile and can be broken easily unless worn.

The following information pertains to an upcoming version (3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

Per commit e9c58c2f, crystal plate mail and other glass armor does not instantly shatter, with the cracking being treated as a form of erosion - a glass piece of armor that has three levels of erosion will be destroyed the next time something would damage it.


Crystal plate mail is the second-highest source of AC in the game that does not inhibit spellcasting after dragon scale mail, and is immune to erosion. However, it is seldom used in practice primarily due to its weight: roles who would most benefit from it typically lack the carrying capacity to reliably carry one, since most roles tailored for spellcasting start with low strength. Most Wizards and other casters that could raise their strength to a sufficient level to consider wearing crystal plate will either have: A) a means of obtaining dragon scale mail, or B) a low enough AC that the additional protection is not worth the weight penalty.

Characters with high strength will usually prefer a dwarvish mithril-coat until they obtain dragon scale mail, and even wearing an elven mithril-coat frees up 300 aum of weight in the inventory while providing only two fewer points of base AC. Characters who do not wish to use metallic armor will usually prefer a studded leather armor. Players still willing to try out crystal plate mail will have to be diligent in their inventory management to avoid being burdened too often.

As crystal plate mail is easily broken unless worn, be careful when handling it: in particular, beware of using force bolts or a wand of striking near a shop selling crystal plate mail, since most early characters will not be able to pay off the shopkeeper if they break any.

Of note is that crystal plate mail has an irregular base price of 820zm, which should be accounted for when price-identifying armor for enchantments.


Crystal plate mail first appears in NetHack 1.3d.



In UnNetHack, Knights get a weight reduction for any body armor heavier than studded leather armor, making crystal plate mail a more feasible option for them in particular.


In dNetHack, crystal plate mail grants 3 AC and 3 DR while worn, but does not confer magic cancellation, and its weight is reduced to 170 aum. For Samurai, crystal plate mail is known as "jade o-yoroi".

Crystal plate mail can safely be enchanted to +7 and adds its full enchantment as a bonus to both AC and DR, rather than half of its enchantment to each as with other armor - dNetHack also introduces crystal armor for each part of the body, which has the same traits.

Crystal plate mail can be found in the second-to-last floor of the Windowless Tower.


In xNetHack, while crystal plate mail is not changed directly, armor with glass as its base material can be shatter-proofed through the usual methods of erosion-proofing armor (e.g. reading a scroll of enchant armor while confused). Worn armor is also subject to a 14 weight reduction, making crystal plate mail slightly more viable.

Dragon scale mail is replaced with dragon-scaled armor in xNetHack, significantly changing which armor is viable or even "optimal" for a given character; crystal plate mail is likely to be overlooked in favor of comparable mail with a lighter material, such as bone or mithril, for use with dragon scales.


In notdNetHack, in addition to dNetHack details, Ymir is generated with a +10 artifact set of crystal plate mail known as the Plates of the Near Void when summoned by an Illithanachronounbinder.


In EvilHack, crystal plate mail is changed considerably: Its weight is reduced to 150 aum, and its base material is gemstone instead of glass, making it immune to erosion (which includes shattering). It is also immune to disintegration and the revamped destroy armor monster spell, which can now erode armor even if the target has magic resistance or the armor is made of an inherently erosionproof material.

EvilHack applies a spellcasting penalty to all roles for any worn body armor similar to SLASH'EM, with crystal plate mail as the sole exception. Dragon scale mail is replaced with dragon-scaled armor in EvilHack as well, and crystal plate mail is among the most enticing armor to merge dragon scales into.

High-ranking mercenaries of a race that can wear body armor have a chance of generating with crystal plate mail as usual. The Paladin, the Infidel quest nemesis, will always generate with crystal plate mail.

The Armor of Retribution is an intelligent artifact set of crystal plate mail that can only be created at a forge by combining The Sword of Annihilation and Ashmar.


  1. src/makemon.c in NetHack 3.6.7, line 622
  2. src/mplayer.c in NetHack 3.6.7, line 174: 12 for barbarians and other mentioned roles to get random body armor within the range of objects from plate mail to chain mail in objects.c, using normal generation odds
  3. src/mplayer.c in NetHack 3.6.7, line 201: body armor for knights
  4. src/mplayer.c in NetHack 3.6.7, line 215: body armor for priests
  5. src/mplayer.c in NetHack 3.6.7, line 242: body armor for valkyries