Stress part of the dialog

How do you stress a certain word of a dialog?

would it be something like:
"Why did you cut the blue wire? I told you very clearly to cut the -red- one."
Wehre 'red' is the stressed word, or something else?

 

You put the stressed words in italics, so it goes something like this: "Why did you cut the blue wire? I told you very clearly to cut the red one."

 

Another vote for italics.

I'd add that you want to use them sparingly. Most of the time, readers should be able to put the right inflections in themselves.

 

Third for italics, and a second for what @Tenderiser said.

 

Another vote for italic, keeping in mind what @Tenderiser mentioned.

 

I don't really think this is up for debate. As has already been said you use italics. End of.

 

Yup. This is one of the primary things that italics are for.