Amazon calculates a product's star ratings based on a machine learned model instead of a raw data average. The model takes into account factors including the age of a rating, whether the ratings are from verified purchasers and factors that establish reviewer trustworthiness.
Opi is my favorite brand. But 1 star is less because: 1. The bottle had a paint or some unclean mark. 2. The rim of the bottle mouth had paint on it already. Hence clearly it was swatched/used product Thats the reason this very product was priced lower(780) than normal (850) Hope this helps all for future purchases.