Which term describes the quality classification for diamonds not suitable for jewelry?

The term that describes the quality classification for diamonds not suitable for jewelry is "industrial quality." This classification is applied to diamonds that are generally too flawed or have poor visual characteristics to be used in fine jewelry. Instead, these diamonds can be repurposed for industrial applications, such as cutting, grinding, and drilling, due to their hardness.

In contrast, gem quality diamonds possess the aesthetic qualities necessary for jewelry, including clarity, color, and cut, and are typically graded for their value based on these criteria. Luxury quality and commercial quality do not specifically refer to diamonds that are deemed unsuitable for jewelry; instead, they typically relate to variations in quality and market positioning within gem quality diamonds. Understanding these classifications helps in differentiating diamonds based on their intended use and value in various markets.