Evolving Budew

[Smashchu]

I know Budew eveolves though friendship but I'm hainve a bit of a problem.

I need to know how many hearts on the happiness checker I need. It has 2 right now. Also, as a follow up, when exactly do you get the shiny stone?

 

[Virtual Headache]

Are the 2 hearts small or big?
If they are big, it will certainly evolve next level.
If they are small, it might aswell evolve, I think it depends on how close to 2 big hearts it is (I've already had a Pokémon evolve with 2 small hearts).