Most diamonds, like people, have natural blemishes that are characteristic of that particular piece. The best way to view these blemishes, or inclusions, is with the use of a 10x magnification loupe. Even though an inclusion may not be visible to the naked eye, it can have an effect when light enters a diamond and is reflected and refracted. If anything is disrupting the light flow, such as an inclusion, a portion of the light that would be reflected is lost.

The certification societies have standardized a grading system to describe the clarity of a diamond. There are two levels of clarity:

  • Eye Clean:  What one can see with the naked eye.
  • Loupe Clean:  What one can see with the magnification of a 10x magnification loupe.

The diamond is of ideal clarity if you can’t see any inclusions with the naked eye (FL to SI2). Better clarity is invisible, but much more expensive and you can see the difference only by microscope.

It is important to keep in mind that some inclusions may be able to be hidden behind a part of the mounting. You can substantially reduce the cost of a diamond if you see that the inclusion will be hidden behind the mounting and not affect the beauty of the diamond. On the other hand, an inclusion on the middle or top of the diamond can affect the dispersion of light and make a diamond appear less brilliant.

You can get an excellent value with diamonds that have Slight Inclusions (SI1, SI2, SI3), but you should consult with the dealer as to whether any of the inclusions can be visible to the naked eye and, if so, will they be able to be hidden by the mounting. Diamonds that are absolutely clear without inclusions-fractures, scratches, or trace minerals are referred to as flawless and are the rarest.