Assigning a different material to an object that is inside a different object

[audra@audrageras.com]

Can anyone tell me if there is a way to assign a different material to an object that is inside another object? - imported from ZBrush 4R8 into Keyshot 7.2.
I have a cell model with a separate nucleus model inside it.  Any materials I try to assign are applied to both. Any way to make the inner model a separate material?
Thanks in advance!

[theAVator]

if they are separate objects in the tree, select the piece in the tree you want to apply the material to, and then drag the swatch to that object in the list (don't drag the material onto the actual object in the viewport).

you can also click on the object in the tree and down at the bottom in properties you can choose unlink material from there as well which breaks the connection, however, I think if you color the higher level object it may still override that?? not 110% though. . 

Subsequently, if you wanted it separate all together, you can use the Edit Geometry option to separate the objects.

[audra@audrageras.com]

Thank you so much. As a relative newbie, I am very grateful for your help!! I will give that a try.