The level of clarity, combined with vividness of colour, are possibly the most important factors affecting the quality and price of most gemstones.
An inclusion free gemstone can command a high price; those that are heavily included can make the gem appear dull and lifeless. Strictly speaking, clarity literally means “clearness” rather than lack of inclusions and refers to the gem’s ability to allow light to move freely through it without obstruction. Nonetheless, clarity is often used to refer to the lack of inclusions. Some gems are naturally clearer than others: Amethyst, Citrine, Aquamarine and Topaz for example should have good clarity. When they don’t their price is substantially reduced.
Other gems such as Ruby and Emeralds are rarely clean and nearly always have inclusions. Along with depth of colour, Clarity is the main reason that Ruby, for example, can sell for between £100 and £10,000 per carat!
As clarity is used more frequently to describe the presence or lack of inclusions, we tend to use ‘transparency‘ or ‘diaphaneity’ when discussing the ‘see through’ of a gem.
