Where the flying fuck can I find this thing. I want to evolve happiny but I haven't been able to find an oval stone yet. I've been farming dust clouds in Clay tunnel mainly but have also done a fair bit in the relic passage and mountain.

I've spent well over 300k on max repels to try and focus entirely on the dust clouds and I've only been able to find about 20 of every gem, and 4-10 of every other type of evolutionary stone. Is the oval stone just a myth that I've been trolled into looking for?