Gemstone Crab: AFK Combat XP and Gem Profit Combined

Most AFK training methods in Old School RuneScape give you experience and nothing else. The Gemstone Crab is different: while you rack up near-effortless combat experience, you also walk away with a steady stream of uncut gems. If you have read our complete Gemstone Crab guide, you already know it is beginner-friendly. This article focuses on the real magic: stacking two rewards from one grind.

Two rewards from one grind

Every relocation of the crab is a chance to earn both experience and loot. The combat experience comes automatically as you attack, and the gem loot comes from mining the shell it sheds when defeated. Because the crab has effectively infinite health and relocates roughly every 10 minutes, you get a continuous loop of both with almost no downtime.

The key insight is that these rewards are not a trade-off. You are not choosing between XP or profit; a well-set-up trip delivers both, and a few smart choices can boost each without much extra effort.

Combat experience with almost no effort

The crab has no meaningful defence and weak attacks, so nearly everything you throw at it lands, and you rarely need food. That makes it one of the most relaxed places to train melee, ranged, or magic in the game. Our AFK combat training guide covers the details, but the short version is:

• Melee is the simplest: equip your best weapon and swap styles to train Attack, Strength, or Defence.
• Ranged is the comfiest: a crossbow lets you attack from range with minimal fuss.
• Magic works too, and casters can add passive Magic experience with Magic Imbue on the Lunar spellbook.

Whichever you pick, the experience rolls in while you focus most of your attention elsewhere.

Turning shell gems into profit

When the crab is defeated it sheds a shell that lasts 90 seconds, and the 16 players who dealt the most damage may mine it (with a pickaxe) for three random uncut gems. Those gems range from common opals and jades all the way up to the rare dragonstone. The full odds are in our loot table breakdown, but the takeaway is that the more damage you deal, the more reliably you make that top-16 cut on busy worlds.

That is why your setup matters even for a "profit" trip. A higher-damage loadout, like ranged with ruby bolts (e), directly increases how often you get to loot the shell. Our gear and setup guide breaks down budget-to-max options.

Cutting gems for passive Crafting XP

Here is where the synergy really shines. Bring a chisel and cut your gems between kills for passive Crafting experience. Now a single session is training a combat skill and Crafting and generating value from the cut gems — three benefits at once. A gem bag helps you stockpile without clogging your inventory on long trips.

If you would rather bank the value, uncut or cut gems sell readily, or you can high-alch them if you are also training Magic.

Why ironmen love it

For ironman accounts, this double-dipping is especially valuable. Gems are a genuine Crafting resource that you would otherwise have to gather elsewhere, so the crab quietly feeds two skills while you barely touch the mouse. That combination of free combat levels and useful materials is why the crab shows up so often near the top of our restricted-account rankings.

Dialing it in

To get the most from every trip:

• Keep a pickaxe so you never miss the 90-second shell window.
• Bring a chisel (and ideally a gem bag) to cut gems for Crafting as you go.
• Use the highest-damage setup you are comfortable maintaining to make the top-16 cut more often.
• Decide how AFK you want to be: tank the light hits for pure background training, or reposition and use specials to push damage.

Put your kills on the board

All that combined XP and profit adds up to a serious kill count over time, so make it count. When you are ready, submit your kill count with a clear screenshot to join the verified leaderboard. Every entry is checked by hand, as explained on our verification page, so your rank reflects real effort. Set up once, settle in, and let the Gemstone Crab pay you twice.