What does the SI designation in diamonds indicate?

The SI designation in diamonds stands for "Slightly Included." This classification refers to diamonds that contain inclusions or blemishes that are noticeable under 10x magnification but are often not visible to the naked eye. These inclusions can affect the overall appearance and perceived quality of the diamond, but they typically do not significantly detract from its beauty or structural integrity.

Diamonds graded as Slightly Included may still exhibit great brilliance and charm, making them popular choices among consumers who want a balance between quality and affordability. Each specific grade within the SI category—whether SI1 or SI2—delves deeper into the extent and nature of these inclusions, but the overarching designation indicates that the diamond has some imperfections.

This understanding of the SI classification is essential for making informed decisions when buying diamonds, as it helps buyers understand how inclusions can affect both the visual appeal and the value of the stone.