Crystal Farming is the same as Myth Stone Farming. each Crystal has a number on it that is the lowest floor it can be found on. Luck increases the chances of higher Tier Crystals dropping. on floor 100, Calcite stops dropping, and higher Tier Crystals have the same chance to drop as the next lower Crystal (Kyanite now has the chance to drop that Larimar had, and so on). for each 100 floors up to 500, the next lowest Crystal doesn’t drop (the 5 lowest at floor 500) (on floor 500, Kyanite has the same chance to drop as Calcite while Calcite, Angelite, Quartz, Diamond, and Larimar don’t drop at all).
using Crystalline Set can increase the chance of higher Tier Crystals to drop even more. I think Crystalline (6) would increase the chance for higher Tier Crystals to drop by +45% and +300% chance for Legend Items dropping with a Crystal affix (if there is an affix on the Item that is on the Crystal Affix List).
some players farm on Very Easy or Easy to kill monsters faster/easier, but you need more space to get your Luck & Gold Find to Cap. when you look at Options > Difficulty Level, it will show you what your bonus is for Gold Find & Luck. just subtract that from the Cap to find out what you need on your Equipment.
here are a bunch of different builds that might give you some ideas for improving your build.
some of these builds are from before Patch 3.0, so they might need a few changes to still be useful. the last one, Explosive Pellets - Arcanist needs Weaken to work instead of Crit chance, so Ignore Resist would have to be taken off (it cancels Weaken affix & Effective Mythic). a more recent Patch 3.1(?) Obsidian Crystal can now also be used to max the values of Crystalline affixes.
hope this helps.