Diamonds and Lemons is a bonus episode of Adventure Time, which aired between the season 9 episodes "Gumbaldia" and the series finale "Come Along With Me." It is the two hundred and seventy-ninth episode overall.
Finn and his friends experience setbacks and creative triumphs in a fantastic new vision of Ooo.
The episode starts off with Finn fighting against numerous zombies and spiders while retrieving a bucket. After several of his tools break, he runs off to the treehouse as the sun rises. On the way, he passes by Lemongrab 3 who is attempting to plant a lemon in the ground. When he gets back to the treehouse he hops in a minecart and rides underground to where Jake is mining for Diamonds. Jake asks for help in digging for diamonds after Finn give some him the water, to which Finn agrees. After they amass a large pile of diamonds, they walk over to lava, as Jake begins to through in diamonds. Finn is outraged, calling it a waste, and says he is going to make something special out of one of the diamonds.
The camera cuts to Lumpy Space Princess, Ice King, Gunter, and Ancient Sleeping Magi of Life Giving are meeting, bragging about griefing houses. Ice King suggests griefing Finn and Jake, but LSP is mad because he has never griefed before, and tells him to grief soon or he will be kicked out of the club.
Finn goes to seek out someone to help with his diamond, and as he passes by Lemongrab, he gifts him a shovel to help plant the lemon. Lemongrab digs a hole, puts the lemon in it, and gets frustrated when nothing happens. Finn goes to where Marceline is summoning skeletons to build a windmill, and he asks if she knows how to blow away Jake with a diamond. She suggests building a windmill out of diamonds, but Princess Bubblegum takes the diamond and makes a firework, which he takes. PB and Marceline give Lemongrab some saplings and bonemeal to help him.
Finn goes to Tree Trunks and Mr. Pig's house where they are playing cards, and he asks for an Apple pie. Tree Trunks is out, but gives him a pumpkin pie as a substitute. Finn rides on Mr. Pig with a carrot on a stick, but runs into an Enderman on the way home. Mr. Pig runs away, but Finn is stuck staring at it’s feet so as not to get attacked. As a day passes, the Enderman still has not left, and Finn is getting very tired. LSP is sleeping under a shack nearby, and as she wakes up she complains to Finn loudly, which causes the Enderman to finally leave. Ice King comes to take a pumpkin out of Finns backpack, but gets scared by the Enderman, who chases him as he puts th pumpkin on his head.
Lemongrab wakes up to discover that his lemon tree has grown, but as he reaches up to pick one, he discovers they are actually apples. As he collapses in defeat, Tree Trunks comes by to pick the apples. We cut back to Finn, who is showing Jake the things he has gotten on his journey as he launches the firework at the roof of the cave. Having judged Jake for throwing all the diamonds away Finn comes up with a philosophic conclusion about the topic of hard work and how the beauty lies in the action itself which drives us to repeat actions to capture this beauty over and over again.
- Princess Bubblegum
- Lumpy Space Princess
- Ice King
- Ancient Sleeping Magi of Life Giving
- Gumball Guardian
- Tree Trunks
- Mr. Pig
- Peppermint Butler
- Snow Golem (intro only)
- Fionna (intro only)
- Cake (intro only)
- Flame King (intro only)
- Party Pat (intro only)
- Mannish Man (intro only)
- Doctor Princess (intro only)
- Lady Rainicorn (intro only)
- Charlie (intro only)
- T.V. (intro only)
- Viola (intro only)
- Kim Kil Whan (intro only)
- Jake Jr. (intro only)
- BMO (intro only)
- Banana Man (intro only)
- Banana Guards (intro only)
- Cinnamon Bun (intro only)
- In the episode, Lemongrab 3 is seen trying to grow a lemon. However, as of this episode's release, there are no lemons in Minecraft.
- Right after the song is played in the opening sequnce, Fionna and Cake briefly replace Finn and Jake.
- The episode's title is a reference to the nursery rhyme Oranges and Lemons.
- The episode is a promotion for the popular sandbox survival videogame Minecraft.
- This is considered a bonus episode as it is not a part of any season. It aired between the season 9 episodes, "Gumbaldia" and the series finale "Come Along With Me," but was produced separately from the main Season 9 order, and is non-canon, separate from the main storyline. 
- In the game Minecraft, Enderman are hurt by water, but the one in the episode stands in rain with no issues.