The Carat is a measurement of how much a diamond weighs. Each Carat is divided into 100 “points”. For example a half-Carat stone is considered a “50 point diamond”. All else being equal, diamond price increases with Carat weight because larger diamonds are more rare, and thus harder to source.
When looking for a diamond, Carat should be used as a guideline but not the determining factor in your selection. Carat is not necessarily the best indication of how large a stone will appear, rather the measurements of the diamond are a more important reflection of “size”.
The Carat selection for your diamond purchase will generally be determined by your budget, so it’s best to set parameters for your price range, assess a range of qualities (Color/Clarity), and then find your preferred balance between size (Carat) and quality (Color/Clarity/Cut).