Medium Rare (internal temperature 145°) steak will be very pink in the center and slightly brown toward the exterior.
Medium (internal temperature 160°) steak will be light pink in the center and brown toward exterior.
Well Done (internal temperature 170°) steak will be uniformly brown throughout.
From "Betty Crocker's Complete Cookbook, Everything You Need to Know to Cook Today, 9th Edition." Text Copyright 2000 General Mills, Inc. Used with permission of the publisher, Wiley Publishing, Inc. All Rights Reserved.