It's pretty sad that I consider this lucky, but after seven years, I finally found the Elvish Jewelry. I may have squealed IRL. I was convinced it was never going to happen and was just doing a regular forage run, not trying for it. Just one artifact to go for the complete collection. I generally have poor luck, but the exception to that is Prismatic Shards (17 so far). Just today I found four in one Skull Cavern run, and two were in the very first and second rock I broke on level 70. Also found the Genie Shoes for the first time ever.
In my latest playthrough, I had found every artifact for the museum except the dinosaur egg. So I spent a lot of time fishing, while knowing that once I caught an egg, I'd have to use it to raise a dinosaur first until it laid another egg, which would take awhile. Finally, at long last, I caught a treasure chest with a dinosaur egg inside it. On the very next cast, I caught a *second* dinosaur egg!
End of spring year one, out fishing, and I find the trident dagger. I didn't have to replace it until the middle of winter
I got two (2) Prismatic shards in one run. Also got genie shoes the next run. What's so special about genie shoes anyway?
Well after 317+ hours I have yet to see them (genie shoes). I only know of their existence because of threads like this. So count yourself lucky.
Nothing other than their rarity, as far as I can tell. But it's cool to get them if you're collecting the drop-only gear for fun.