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.
I've had the single old fashioned and highball glasses over a year. They catch the light beautifully and are always elegant. As long as I take reasonable care when loading them in the dishwasher they are reasonably durable, too. Such pleasure to use for guests and personal use.