Dark sapphires show fewer inclusions but lack the fire and brilliance of their lighter counterparts. Sapphires should be eye-clean at wrist length with slight inclusions visible under a 10x scope. Nearly everyone wants the most perfect gem, but perfection in the precious colored gems may be impossible. The common unit of measurement for gemstones is weight and is expressed in carats. Do not confuse weight with size.
Some stones weigh more than others because stones have different density.
The carat weight of a stone is the unit used in pricing of the sapphire. The durability of a sapphire is based on the Mohs Hardness Scale. Diamonds are the hardest stone, rated at 10.