Big Emerald

Verified against the spelunky.ai port v0.1.10 on 28 October 2026.

It's the cheapest of the three big gems, below the Big Sapphire and the Big Ruby, and worth four times a small Emerald. Level generation buries Big Emeralds in rock and sets them in nooks in every area, and Jars, Chests and a few monsters let them out. The player collects one by touching it; a Ghost that touches one turns it into a Diamond.

A Big Emerald's base value is $800, and it's worth a quarter of that more for each area past the Mines, the code counting Olmec's Lair as an area of its own ^{[2] [3]}:

Each block of rock that isn't a gold vein (71 in 100 aren't) and isn't on the level's edge rolls for a big gem inside it. The Big Emerald's roll comes once the Big Sapphire's fails:

The Tutorial's bricks roll as the Mines' do ^[8]. In the Temple, one block of rock in 100 is the Jungle's earth, which rolls at the Jungle's odds, and one in ten a stone block, which holds no gem ^{[9] [10]}. The City of Gold's temple blocks are gold instead, and don't roll for gems ^[11], but its blocks of earth still do ^[12]. A buried gem stays where it is, hidden behind the rock, until the block around it is destroyed, by a Bomb or a Mattock for instance; then it drops out. With the Spectacles or the Udjat Eye, treasure is drawn in front of the rock, so the buried gems show through it ^[13].

Level generation gives each block outside a shop with open space above it, away from the entrance, the exit and a Golden Idol, a roll for what lies on it, in every area, once its rolls for a Rock (1 in 100) and a Jar (1 in 40) fail ^[14]. A big gem comes late in it:

On a Mines level that's still to place the Udjat Eye's locked chest, a nook that gets no web rolls for the chest and nothing else ^[20]. On a level with the chest, level generation then turns one treasure that isn't inside rock, picked at random, into the chest's key ^{[21] [12]}. The Tutorial has one lying on a high ledge ^[22], and the level editor's 5 tile is one ^[23].

The player collects a Big Emerald by touching it while he isn't stunned or dead; the one he takes is the treasure nearest him, one a step ^[30]. It's made uncollectable, and its own alarm, set to 20 steps (0.67 seconds) when it's made, makes it collectable ^{[31] [32]}, so one fresh out of a Jar, a Chest or a monster lies a moment before the player can take it. In the clip, the player climbs to a high ledge of the Tutorial and runs along it over a Big Emerald, a Big Sapphire and a Big Ruby, collecting each as he touches it ^[33].

In the second clip, a whipped Jar lets out a Big Emerald and a Gold Chunk, and the player walks over them: his money goes up by $900, the Big Emerald's $800 and the chunk's $100 ^[34]. It lets out two treasures because a whipped Jar rolls its contents twice (Double Jar roll).

Its value shows under his money and is counted into it after a short pause; whatever is left is counted at once when he leaves the level ^{[35] [36]}. A gem plays its own sound, where gold plays the coin's ^[37], and the screen between levels shows each Big Emerald collected on the level ^[38].

A loose one falls and comes to rest like other treasure, moving only while it's on the screen; a Web it falls into holds it, and lava it sinks into destroys it ^{[39] [40]}.

The Ghost. A Ghost that touches a Big Emerald turns it into a Diamond, in the same place ^[41]. The Ghost drifts through walls, so it does this to gems still buried in the rock too ^{[42] [12]}.

• Only the three big gems have code for a Ghost's touch, so a Ghost passes over the small gems, gold and a Diamond and leaves them as they are ^[41].