Google AdWords offers seller ratings for shopping related ads, as well as other ads. These are an automated extension type that showcases advertisers with high ratings. Google will collect seller ratings from reputable sources that aggregate business reviews. This AdWords ad extension shows below the ad and looks like this:
Many advertisers who are new ask why they don't see these seller ratings for their sites. Well, it normally takes at least 12 months of data aggregation for Google to start showing these ratings. Often it also requires at least 150 unique seller reviews over the past 12 months. If you do not have 150 reviews in the past month, you might lose those ratings.
The help docs read:
For Google Shopping star ratings to appear, typically your business needs at least 150 unique seller reviews, each from the past 12 months. However, we may show ratings for merchants with fewer than 150 reviews if we have sufficient data from other sources to determine an accurate rating.
Google was asked this on Twitter:
@DennisGriemink Hi Dennis, Google looks at the last 12 months worth of data from various sources when generating seller ratings. (1)
— Google AdWords (@adwords) December 6, 2016
Forum discussion at Twitter.
This post was scheduled to go live today but was written earlier - I am currently offline today.