Is it appropriate to use review markup for testimonials without numerical rankings

[Oren.]

If a site has written testimonials from past clients, what is/is there an appropriate way to mark these up in schema since they don't have a specific numerical rating attached to them?

[Whebb]

Hello Oren,

Most of the information I have seen requires some kind of rating number or data in order for reviews to show in the SERP.

If you look at google's guidelines for setting up structured data for an individual review, https://support.google.com/webmasters/answer/146645?hl=en#individual , you will see the 'rating ' is one of the properties. If you set this up without the rating property and then ran it through the rich snippet testing tool you will see an error and therefore the data will not be displayed in the SERP.

Also, in my experience, ratings structured data can be a bit finicky too, if the markup is not 100% accurate, then they do not display.

Hope that helps.