A two-carat blue sapphire's worth is not just based on how much it weighs. A number of important elements add to its value. The color is the most important of these. Known variously as "cornflower blue" or "royal blue," this deep, rich color is expensive. Clarity is also important; the most expensive stones are those without impurities or imperfections. The 2 carat Blue sapphire cut also affects its fire and brilliance; well-proportioned cuts maximize light play. Treatments that improve color, such heating, can also have an impact on cost.