Fashion Gems

@SalixCat Could you please make for the new players a tutorial explaining Izzy, fashion gems, stickers, and how to earn them?

I'm a pretty experienced player, and I know how it all works, but I ask because I had a question about fashion gems and tried to search for an answer and found very little info about this. 

My question is this: how many stickers in each category must we get to receive the maximum (9) number of gems? Or is it that we have to get a certain number of stickers total? 

Thanks for your help Salix!