In floor 500, the drop of crystals is +5 tiers so instead of calcite , you get 5 tiers above and that applies to every crystal. That means Jasper will be Obsidian drops and the chance of an obsidian drop is as high as a random Jasper crystal drop. Kyanite will be as common as calcite though which makes crystals dirt cheap for map rerolls . Also emeralds will be as common as the diamond crystal so very common and many crystals will just be overall common.
It's how I managed to get 1000s of many crystals to convert so I could try to get 99 of each. The same for mythstones if you want high their mythstones easier such as Elixir. Elixir becomes as rare as fortune which means it's a bargain and it makes building easier for a beginner. It's how I never have to hunt mythstones anymore and many other players.