Diamonds are the rare form of Ore. You can sometimes find Diamonds in the bazaar, but Diamonds are collected just randomly as you collect Ore; they are just rarer. I suggest that you buy the Transmute Diamond recipe from a crafting vendor it lets you change 15 Ore into a Diamond. Good luck!
Diamonds are a rare reagent that sometimes drops when you harvest ore. If you grab every chunk of ore you come across, you'll often harvest additional ore, and sometimes a diamond.
Diamonds may be crafted using ore. To do this, buy the Transmute Diamond recipe from Felicia Worthington in Marleybone, then use your Card Crafting Station. Page over through your recipes until you get to the Reagents section. Each recipe consumes 15 ore and produces 1 diamond.
Both ore and diamonds are sold in The Bazaar, but it takes some effort to get what you need. Even so, if you have the gold to get them, this is far and away the fastest method to getting diamonds.
My recommendation: Open up Elik Silverfist's screen to begin trading. Page over to the reagents, snacks, and garden spells section. Click Reagents, then go down a page if need be. Reagents are sorted alphabetically. If you don't see diamonds, simply click the Reagents item again, causing the screen to reload. Every few minutes, another player will sell their diamond(s), giving you a chance to buy them. Unfortunately, lots of other players want these, so they sell very quickly.
I had to buy diamonds a few days ago. What I found was that other players often bought any diamonds I saw before I could complete my purchase. I finally figured out that clicking the Buy button and immediately hitting the <Enter> key to confirm the purchase worked best. Buying ore isn't quite so much of a hassle, but you'll need a lot more of it.
