Shouldn't lab-grown diamonds be perfect because they're man-made? Can not. Although they are carefully grown in a laboratory, lab-grown diamonds are not perfect. Lab-grown diamonds are made under conditions very similar to those on Earth that form natural diamonds. Diamonds develop defects as they grow in both processes.
Colorless or white lab-grown diamonds range from pale yellow/brown to true colorless. The same color scale is used to grade lab-grown and natural diamonds.
Lab-grown diamonds may contain inclusions that affect their clarity grade. Inclusions are tiny defects that form during diamond growth. In natural diamonds, these defects can arise from foreign substances (water, gases, or other minerals) that entered the diamond's structure during diamond growth. Natural diamonds can also have tiny cracks because they are formed under very high pressure.
Similar fractures can also form in lab-grown diamonds because they are grown under the high pressures of the lab. Graphite inclusions are also common inside lab-grown diamonds. Graphite is just another form of carbon. (All diamonds, natural and synthetic, are made of carbon).
Most inclusions in lab-grown diamonds are so small that they cannot be seen without magnification. The same goes for natural diamonds. Lab-grown diamonds have the same clarity grade as natural diamonds.
The cut and carat of lab-grown diamonds are evaluated in the same way as natural diamonds. However, lab-grown diamonds have an interesting advantage in the cutting process. All excess material cut from a polished diamond gemstone is discarded, which ultimately reduces the diamond's carat size. Some diamond cuts will skimp on the cut to maintain the size of the diamond, resulting in a good or very good cut, but not ideal or excellent. This is more common if the diamond is larger or near the coveted 1 or 1.5 carat weight. The price of natural diamonds also increases exponentially with carat size, as large diamonds are rare. For lab-grown diamonds, this is not a problem, as they can be grown according to the size determined by the lab.