Does your rendering look like this:
This is happening because there are two surfaces occupying the same space. One that is using a glass material, the other is using the dark liquid material. The software tries to display both of them, but an interference pattern results. You will need to select the object with the glass material and turn it off. you can do this in Rhino, but if you are already in Keyshot, you can do it there as well. There are two ways to do this:
This page shows how to use the scene tree to select an object and turn it off
But you can also delete it. From the scene tree, select the object you want to delete and then right click and select delete from the list of options (shown here):
In Rhino, you can also run the command SelDupAll (Edit>Select>Duplicate Objects) to find any duplicates that might be in your model.
This link provides an illustrated explanation. It’s geared towards SolidWorks users, but the concept is the same.