What can you do with diamonds?

[De Belastingdienst]

Beside giving as a gift?

[Hurodrik]

I had a job board quest to deliver one once, so now I always keep one or two stored. Aside from that, they have a nice sale price.

[Zourin]

There was a book talking about a crystal replicating devices. Crystalarium, i believe.

[Hurodrik]

Originally posted by Zourin:

There was a book talking about a crystal replicating devices. Can't confirm anything atm :/

Yep, you can "gain" that device in the vault room of the Community Center. It's one of the more expensive unlocks.

[JKerman511]

i have about twenty, and i'm not sure what to do with them.

[I Kinda Fail]

Sell 'em. Keep a few. They're "loved" gifts for a few people. I dunno who all, but Gus, Evelyn and Marnie love them. And everyone "likes" them, but they sell for 750, so I would save them for loved gifts.

I don't think they're used in any crafting recipes, if that's what you're asking.

Occasionally the job board will have someone ask for one, and they'll pay you somewhere between 2-3k for one, plus it makes them super happy.

[Fallow]

According to the wiki, they are an ingredient in crafting a Ring of Yoba, a ring that occasionally shields you from damage. Which... doesn't sound like a must-have item especially since you have to already be at Combat level 7 to get the recipe to craft it.

So yeah, diamonds as a gift are either loved or liked by everyone and nobody dislikes them, so if you have one then put it in the crystalarium to replicate and just store them up to use as gifts for people or sell them if you need the money.

[Nakos]

I keep a few of everything "just in case", and that includes diamonds, but ... mostly I just sell them.

[Volcott]

Yeah, keep one or two in reserve for the quest board, sell the rest.

[CommandConquer]

Shove them into a crystalarium to make more diamonds and just sell them.

[Smeggit]

Minor spoiler if you haven't gotten to your 3rd year: You can use diamonds in Grandpa's Shrine to re-evaluate your progress.