SI1 Clarity

What SI1 Clarity Means for Buyers

SI1 is a point on the GIA clarity scale, which grades how many and how visible the internal inclusions and surface blemishes are at 10× magnification. The top of the scale is FL (flawless); the bottom is I3. The key word for buyers is 'eye-clean'. Whether you can see any inclusions without magnification. And that threshold is closer to the middle of the scale than most buyers assume.

Right now we're tracking 1,989,145 active SI1 clarity listings across our retailer network. The typical natural SI1 diamond trades around €1,766/ct while the lab-grown equivalent sits at €609/ct. Roughly a 66% gap that reflects the broader natural-vs-lab pricing gap, not a quality difference at this grade.

At -4.1% above the neighboring SI2 grade, the premium for SI1 is subtle. Barely enough to move the needle on total budget. Unless you specifically want the paper grade, SI2 is interchangeable for most buyers and leaves money on the table for cut or carat weight.

SI1 shows up most often in ROUND. About 910,429 listings at this moment. Followed by OVAL. Most of the supply clusters around the 0.5-0.99ct carat range, where demand is strongest and retailers keep the deepest inventory. If you're shopping an unusual shape or carat, expect thinner selection.

VS2 is typically eye-clean for almost any shape up to around 2 carats. SI1 is often eye-clean too, especially in brilliant-cut shapes like round and oval that hide inclusions well. But always check the plot or a high-resolution photo before buying SI-grade. Step-cut shapes (emerald, asscher) show inclusions more. Lean toward VS1 for those. Paying for VVS or FL is almost entirely about paper value, not what you'll see.