Virtually all diamonds contain identifying characteristics, yet many of these characteristics are invisible to the naked eye. Under the scrutiny of a jeweler's 10x-magnifying loupe or microscope, natural phenomena within a diamond—called inclusions—can be seen. Inclusions are often thought of as birthmarks that resemble tiny crystals, clouds, or feathers.

An inclusion’s size, color, type, frequency, or position determines a diamond’s clarity, and by default, its value. Major inclusions interfere with the way light travels through a diamond, thusly diminishing its brilliance and sparkle. Diamonds categorized as internally flawless reveal no such inclusions and are therefore determined to have the utmost clarity and value.