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.
Product is quite good and regularly but it. But my experience from Amazon was not good. Half the bottle was empty. Since this is an expensive product, next time I bought it directly at Kama Ayurveda shop.