Polish Grade
The GIA has designed a diamond Polish scale that closely resembles the Symmetry scale. The grades are determined based on the visibility of polish lines or blemishes on the diamond’s surface. This assessment is conducted by gemologists using 10x magnification.
Excellent: No visible polish lines or blemishes at 10x magnification. Light can flawlessly enter and exit the diamond, ensuring its sparkle and brilliance are unaffected.
Very Good: Minor polish details can be observed at 10x magnification. These lines or blemishes may slightly or not at all affect the diamond’s sparkle. An Excellent cut grade is still attainable.
Good: Some polish lines or blemishes are visible, generally only at 10x magnification. The diamond’s sparkle might be compromised as light doesn’t penetrate perfectly. The highest cut grade achievable is Very Good.
Fair & Poor: Noticeable finishing errors manifest as polish lines or blemishes. These defects impair light performance and reduce the diamond’s sparkle. A Good cut grade is the maximum achievable.
FAQs
What does polish mean on a diamond?
Polish is essential for determining a diamond’s brilliance. It refers to the smoothness of each diamond facet, which impacts how light transmits through the diamond.
How are diamonds polished when being cut?
Diamonds are polished using a polishing wheel that smooths the facets of the cut diamond, optimizing light reflection. Polishing is crucial as it determines the diamond’s fire and brilliance.
How important is the polish grade?
The polish grade is highly significant as improper polishing can detract from a diamond’s sparkle. The GIA scale evaluates polish lines and blemishes visible under 10x magnification.
Do lab diamonds have the same polish grades?
Yes, lab diamonds are graded similarly to mined diamonds as they share the same physical, optical, and chemical properties, differing only in origin.