Gemstone Crab

This article has a strategy guide. All information on mechanics and strategy will be on this page.

Gemstone Crab
Released								23 July 2025 (Update)
Members								Yes
Combat level								160
Size								5x5
Examine								The shiniest crustacean this side of the shoreline.
League region								Varlamore✓
Combat info
XP bonus								-12.5%
Max hit								1
Aggressive								Yes
Poisonous								No
Attack style								Crush
Attack speed								7 ticks (4.2 seconds)
Combat stats
∞				1				1				1				1				1
Aggressive stats
+0				+0				+0				+0				+0				+0
Melee defence
+0								+0								+0
Magic defence
+0												No elemental weakness
Ranged defence
+0								+0								+0
Immunities
Poison								100% resistance
Venom								100% resistance
Cannons								Immune
Thralls								Immune
Burn								Immune (strong)
Freeze								100% resistance
Open in DPS calculator
Advanced data
Monster ID								14779
Link								MOID

Gemstone Crab Shell
Released								23 July 2025 (Update)
Members								Yes
Location								Tlati Rainforest
League region								Varlamore✓
Options								Mine
Examine								The sparkling shell of a giant crab.
Advanced data
NPC ID								14780
Link								MOID

The Gemstone Crab is a world boss that moves between three mines in the Tlati Rainforest approximately every 10 minutes. It has no defence, low offensive stats, and effectively infinite hitpoints, making it ideal for combat training, and can be fought in large groups. The only requirement to fight the crab is completion of Children of the Sun in order to access Varlamore.

The health bar of the crab is not affected by player damage, regardless of how many players are attacking it. Instead, it depletes over time to indicate how long until the crab will burrow to its next location. The crab remains stationary for approximately 10 minutes until its health bar is fully depleted, after which it will burrow underground to relocate. At each of the three mines, a cave can be crawled through to quickly take players to the crab's current location and continue the fight.

While fighting the crab, players earn 12.5% less experience per hit than usual, at 87.5% the usual experience (1 damage = 3.5 experience, rather than 4). Despite this experience reduction, the Gemstone Crab typically offers higher experience rates than other commonly killed crabs because there is less overall downtime and no experience is lost from overkill damage (e.g. rolling 15 damage would normally grant 60 experience, but if an enemy has only 1 hitpoint, you would receive only 4 experience). Other crabs will still provide marginally higher experience if the player has a low max hit.

Warning: Though unlikely, it is possible to take small amounts of damage and be killed by the crab. Players, especially hardcore ironmen, should be cautious when low on hitpoints.

The Gemstone Crab spawns in any one of three locations within the Tlati Rainforest.

Location	Levels	Members	Spawns	Map	League region
Tlati Rainforest	160		3	Show map	Varlamore✓

The Gemstone Crab can be easily located by accessing any of the caves near its spawn points. These caves always lead to its current location. Therefore, it is recommended to travel to the nearest spawn and use the cave network, rather than world-hopping. There are a few main ways to reach these spawns:

• Pendant of Ates to Kastori (after activating the corresponding Statue of Ates)
• Fairy ring code AIS to Auburn Valley, run south-west along the River Varla, take Achilka's boat service to Kastori or Tal Teklan
• Quetzal Transport System (requires starting Twilight's Promise) via Renu:
  • Tal Teklan and Kastori both have landing sites that are similar distances. Tal Teklan's site is already built, while Kastori's needs to be built by the player before it can be used. A few common ways to reach Renu are:
    • Civitas illa Fortis Teleport
    • Hunter cape teleport to the Hunter Guild
    • Quetzal whistle to the Hunter Guild
    • Varrock Teleport, run to the east gate, travel to Civitas illa Fortis with the quetzal Primio
    • Charter Ship to Civitas illa Fortis and run west
    • Fairy ring code AIS to Auburn Valley and run north-west to Renu
• Charter or fly to Civitas illa Fortis and run north-west to Quetzacalli Gorge. Follow the mountain guide on the west side of town to Auburn Valley and run south to Achilka's rowboat, then travel to Kastori and run north.

• Ruby bolt (e) special attacks treat the boss as if it has 300 Hitpoints and deal 60 damage, increased to 66 if using a Zaryte crossbow.
• The Gemstone Crab does not count towards Slayer tasks, so players will not receive a damage or accuracy bonus from a Slayer helmet or black mask.
• A dwarf multicannon cannot be placed in the crab's vicinity.
• Thralls are unable to attack the Gemstone Crab, even though they can be summoned near it.
• The Gemstone Crab can be walked under while it is active, though its normal attacks can target and damage players if they stand in the quadrant it is focusing its attacks on. The centre tile of the 5x5 square it occupies is safe from attacks from all sides, though all players standing underneath will be shoved out when the Crab burrows with the message The burrowing crab forces you out of its way..

Once the Gemstone Crab's health bar reaches 0%, it will burrow, shed a piece of its shell, and move to the next spawn location. The shell will remain for 90 seconds before disappearing into the ground. The 16 players who dealt the most damage to the crab may mine the shell for three random unnoted uncut gems, ranging from opal up to dragonstone.

If the player is among the 16 players who dealt the most damage, the message You gained enough understanding of the crab to mine from its remains. appears when the crab burrows away.

If the player is not among the top 16, attempting to mine the shell produces the message Your understanding of the gemstone crab is not great enough to mine its shell.

Gemstone Crab Shell
Level required					1
Mining XP					0 xp
Required tool					Pickaxe
Respawn time					N/A

Drop rates are estimated based on 84,585 samples from the Drop Rate Project, unless otherwise cited.

	Item	Quantity	Rarity	Price	High Alch
	Uncut opal	1	3 × 9/32	76	12
	Uncut jade	1	3 × 9/32	148	18
	Uncut red topaz	1	3 × 6/32	1,865	24
	Uncut sapphire	1	3 × 3/32	228	15
	Uncut emerald	1	3 × 2/32	473	30
	Uncut ruby	1	3 × 2/32	1,087	60
	Uncut diamond	1	3 × 1/32	2,439	120
	Uncut dragonstone	1	3 × 1/500	14,976	600

• Concept art for the gemstone crab, by Mod Jerv.
• A group of players fighting the gemstone crab.

• The examine text appears to be a reference to Tamatoa, a giant crab from the Disney movie Moana who performs a song called "Shiny".
• If the player has an open gem bag in their inventory when mining the Gemstone Crab, they will not receive the chat message "You mine an uncut ____ from the crab shell." when mining precious gems (i.e. those storable in the gem bag).
• The crab will occasionally burrow and immediately reappear in the same location instead of moving to the next. This may be a bug and will result in the crab's shell appearing in the same location as the crab.
• The gemstone crab was inspired by a community Reddit post.^[1]
• As of 9 August 2025, 2,265 players have been slain by the gemstone crab, with 14 being hardcore ironmen.^[2]
  • The number of hardcore ironmen slain had increased to 34 as of 29 August 2025.^[3]
• As of 5 September 2025, players have picked up a total of 1.68 billion coins' worth of ammunition used at the boss.^[4]
• Although the crab's real health bar is not displayed in game, its combat level of 160 would suggest that it actually has between 637 and 640 hitpoints.
  • Enchanted ruby bolts deal 60 damage, implying it has 300 hitpoints and contradicting the combat level.
• The gemstone crab and its shell had a festive override wearing a Santa hat during the 2025 Christmas event.
• The Minion summon from the Demonic Pacts League states that it "will not fight against Yama", but it will also not attack the Gemstone Crab.

v t e Bosses
World bosses	The Hueycoatl Scurrius Giant Mole Deranged archaeologist Sarachnis Kalphite Queen Corporeal Beast Gemstone Crab The Barrows Brothers Ahrim the Blighted Karil the Tainted Dharok the Wretched Guthan the Infested Torag the Corrupted Verac the Defiled The Dagannoth Kings Dagannoth Prime Dagannoth Rex Dagannoth Supreme God Wars Dungeon Kree'arra Commander Zilyana General Graardor K'ril Tsutsaroth Nex Moons of Peril Eclipse Moon Blue Moon Blood Moon The Wilderness bosses Revenant maledictus Chaos Fanatic Crazy archaeologist Scorpia King Black Dragon Chaos Elemental Vet'ion (Calvar'ion) Venenatis (Spindel) Callisto (Artio)
Instanced bosses	Amoxliatl Brutus (Demonic) Royal Titans (Branda the Fire Queen) (Eldric the Ice King) Zulrah Vorkath Phantom Muspah The Nightmare (Phosani's Nightmare) Yama Doom of Mokhaiotl Maggot King Mad Angel Sporadic bosses Obor Bryophyta The Mimic Hespori Skotizo The Forgotten Four The Leviathan The Whisperer Vardorvis Duke Sucellus
Slayer bosses	Shellbane gryphon Grotesque Guardians (Dusk) (Dawn) Abyssal Sire Kraken Cerberus Araxxor Thermonuclear smoke devil Alchemical Hydra
Minigame bosses	Crystalline Hunllef Corrupted Hunllef TzTok-Jad TzKal-Zuk Sol Heredit
Skilling bosses	Tempoross Wintertodt Zalcano
Raids	Chambers of Xeric Tekton Vanguard Vespula Vasa Nistirio Muttadile Great Olm Theatre of Blood The Maiden of Sugadinti Pestilent Bloat Nylocas Vasilias Sotetseg Xarpus Verzik Vitur Tombs of Amascut Akkha Ba-Ba Kephri Zebak Tumeken's Warden Elidinis' Warden