If you're considering polished concrete one of the many things you need to keep in mind is, how flat is you concrete.
The reason you want to ask yourself this is because more often than not your slab will have peaks and furrows which means you will have high points and low points. On the peaks the stone in the concrete will show through larger and the furrows the stone will be smaller. This has to do with the way the concrete was poured and care was not taken to get the slab flat. Unfortunately grinding machines will never completely take out the peaks and furrows and you will be left will a slightly uneven stone sizing.
This random assortment of stone sizing is often a great look and adds a lot of character to the finished product. In my opinion, just like in the lives we lead there are many ups and downs, many imperfections and parts that have needed to be patched up at some point. This is reflected in your concrete floor, your floor is telling a story and that’s the beauty of it.