Inclusions are like fingerprints, a characteristic that gives us all a special signature. Getting to know your diamond inside and out makes the stone a more personal possession—and will help you describe and identify the gem if it is ever lost or stolen.
Some inclusions affect a diamond's clarity, making it less brilliant because they interfere with light as it passes through the stone. Other types of inclusions can make a diamond more vulnerable to shattering.
There are few perfect diamonds, and the ones that are perfect are quite expensive, so the diamonds we buy all have varying amounts of internal and external flaws. Most jewelers tell us not to worry about diamond inclusions if they do not affect the stone's strength or seriously impact its appearance.
Types of Diamond Inclusions
Crystals and Mineral Inclusions
Diamonds can have tiny crystals and minerals embedded in them, even other diamonds. Many cannot be seen without magnification, but a large chunk or grouping of crystals that detracts from a diamond's appearance lowers its clarity grade, and its value.
There are times that a small crystal can add character to a diamond. A diamond with a tiny garnet inside would be a conversation piece -- and a nice personal choice for someone whose birthstone is a garnet.
Pinpoints are tiny light or dark crystals in diamonds and other gemstones that can either appear by themselves or in clusters. Larger clusters of minute pinpoints can create a hazy area in the diamond, called a cloud, which affects the diamond's clarity.
Laser lines are not a natural diamond inclusion. These vapor-like trails are left behind when lasers are used to remove dark inclusions from the diamond. The machine-made trails look like tiny strands of thread that begin at the diamond's surface and stretch inward, stopping at the point where the inclusion was removed.
Feathers are cracks within the diamond that resemble, well... feathers. Small feathers do not usually affect a diamond's durability unless they reach the surface on the top of the stone, a location that's prone to accidental blows.
Diamond cleavage is a straight crack with no feathering. A cleavage has the potential to split the diamond apart along its length if it is hit at the correct angle.
Small cracks that are not visible when a diamond is viewed in a table-up (face up) position do not seriously affect clarity ratings.
Girdle Fringes, Bearding
Girdle fringes, or bearding, are hair-like lines that can occur around the girdle during the cutting process. Minimal bearding is usually not a problem, but extensive fringing is often polished away or removed by re-cutting the diamond.
Grain Lines, Growth Lines
Grain lines are created by irregular crystallization that takes place when a diamond is formed. Colorless grain lines do not usually affect diamond clarity unless they are present in large masses. White or colored grain lines can lower a diamond's clarity grade.
Always shop for diamonds at a jewelry store you trust and find someone who can answer your questions about the diamonds you are considering. Ask the jeweler to show you each diamond under magnification and explain its characteristics to you.