SI3 (Slightly Included 3, EGL only)
A clarity grade recognised only by EGL, not GIA or AGS. Sits between SI2 and I1.
SI3 (Slightly Included 3, EGL only): A clarity grade recognised only by EGL, not GIA or AGS. Sits between SI2 and I1.
SI3 is a non-standard grade used by some EGL laboratories to describe stones between SI2 and I1. GIA, AGS, IGI, and other major labs do not recognise this grade. Buyers should understand that an EGL SI3 would often grade as I1 under GIA standards. When comparing SI3 stones to GIA-graded equivalents, assume a one-to-two grade conservative correction for transparency.
Standards bodies: EGL
Frequently asked questions
Does GIA recognise SI3?
No. SI3 is used only by EGL and some smaller labs. GIA stops at SI2 before I1.
Is an SI3 the same as an I1?
Often yes, in GIA terms. An EGL SI3 would frequently grade as I1 under GIA's stricter standards.
Should I buy an SI3 diamond?
Proceed carefully. The grade disparity means you may be paying SI-tier prices for an I-tier stone. Request a GIA re-grade or discount accordingly.
Which labs use SI3?
EGL primarily. Carat Hunter tracks which lab certified each stone and adjusts comparison accordingly.
Are SI3 diamonds ever eye-clean?
Rarely. At this level, inclusions are typically visible or come close to the limit of visibility.
Related terms
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