Open google places api, place id page
Type in the name of the business you want to find a link for
Then click on the name from the dropdown list
You can see the place id code now
Highlight just that code and copy it
The url you want is like
https://search.google.com/local/writereview?placeid=ChIJcQEaGko-c2sRvWXCH91cKH0
but replace the code with yours instead of the jezweb one.
So you get this bit
https://search.google.com/local/writereview?placeid=
and then put your places code bit after the equals sign, no spaces!
If you send someone that link, or you could use a url shortener if you want, then they will get a popup on their screen from the places page for the business like this.
Thanks to getfivestars for this tip