There are no perfect diamonds. Created by nature, they are all essentially imperfect, and rough crystals contain various substances. These imperfections are judged, and whether they are removed or left intact is decided at the same time of the diamonds’ polishing.

The three diamonds to the right are all SI1(Slightly Imperfect, 1) stones, but A contains a colorless crystal inclusion, B a black inclusion, and C a cleavage near the girdle. All of these imperfections are invisible to the unaided eye, and the diamonds are beautiful, brilliant stones that fall under the gem-quality category. The question is whether or not the imperfection is a defect. The inclusion in stone A does not detract from its beauty or affect its durability. Rather, the inclusion is proof of the stone’s natural origin, making it easy to separate from synthetic materials. A diamond cutter friend of mine in Antwerp always gets SI-grade diamonds like stone A for his wife.

The black inclusion in stone B is an unpleasant one, and the cleavage in C is likely to cause the stone to break id a strong force is applied to it. Both of these are defects. If a jeweler’s policy is not to use diamonds with black inclusions or cleavage around the girdle, stones B and C would be worthless to that jeweler. Trustworthy jewelers would never think of hiding cleavage in a diamonds, as seen in stone C, beneath prongs when making jewelry.