Product ratings are the most common source of social proof in ecommerce. So when you show product ratings (of course, it is assumed that these are good ratings) already on product categories, you start influencing on a customer decision making and increase the likelihood of customers taking action on a purchase.
Also, when you show product ratings, you simplify the comparison of products for shoppers: it will be an additional attribute that can be taken into consideration. Moreover it will be a trust signal about your products and your company.
When adding product ratings, make sure that it's prominent enough. For example, yellow or orange color of ratings (these are the colors that are usually used for that element) will be much more prominent and noticeable than black or grey color. Also don't forget to show number of reviews, as the power of product ratings with thousands of reviews much influential compared with products ratings with a few reviews. Guidelines:
Bad example on MVMT website:
- Show product ratings below product title;
- Use prominent and popular colors for star ratings: yellow, orange or brand-one according to design of your website;
- Show number of reviews.
They have hundreds of reviews on these watches, but product ratings are not visible on category pages. They don't fully use the power of social proof that they already have.