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Diamond Polish
Diamond Polish

Diamond Polish

The term "polish" refers to the overall condition of the surfaces of a finished diamond. A rating is assigned based on the amount of polishing lines that are visible. These polishing lines are caused by very small diamond crystals which are embedded in the polishing wheels used by diamond cutters to polish the surface of the diamond after cutting. Diamond polish is important because it can affect the degree to which light is able to pass through a diamond, rendering it more or less brilliant. Diamonds that are laboratory certified with a good, very good, or excellent polish rating are the most desirable. Diamonds that have poor polish will be less brilliant and not as desirable or valuable. Reputable jewellers diamonds are graded after examining the diamond facet by facet. They are then assigned one of these five polish ratings:

Polish Polish Description
Excellent Not visible.
Very Good Not visible to the unaided eye.
Good May be visible to the unaided eye.
Fair Visible to the unaided eye.
Poor Visible to the unaided eye.

To the unaided eye, 'excellent' and 'very good' ratings are hard to decipher. The differences become visible only when a stone is magnified. A rating of 'fair' or 'poor' means that the flaws in the polish are noticeable to the unaided eye and will have some effect on the overall beauty of the diamond.

Diamond polish vs unpolished

Diamond Unpolished vs Polish.

Poorly polished facets may reduce the intensity of a diamond's reflected light or light which is refracted into and out of a diamond. This can affect the brilliance and visual performance of diamond. When a diamond has a 'good' or lower polish grading, the stone may appear as if it needs to be cleaned.

For diamonds with a polish grade of Excellent to Good, any polishing defects are not visible to the naked eye, and should have no impact on the diamond's overall appearance.

For diamonds with clarity grades of I1 or lower, even a polish grade of Fair is acceptable, since these diamonds already possess internal inclusions* that are visible to the naked eye, making any polish markings less relevant.

For diamonds less than .75 carats, any polish grade of Fair or better will not affect the appearance of the diamond to an untrained observer.

Poor is the only polish grade that should be avoided regardless of the size or clarity of the diamond.

* An inclusion is an internal flaw in the diamond. The position, size, number, color, and reflectivity of a diamond's inclusions has a significant impact on its appearance and value. Clarity refers to the degree to which these natural flaws are present. Diamonds graded by the GIA and other labs have their clarity rated on a scale of F (flawless) to i3 (significant inclusions).