What is a characteristic or irregularity confined to the surface of a polished gemstone known as?

The term for a characteristic or irregularity confined to the surface of a polished gemstone is known as a blemish. Blemishes refer specifically to surface imperfections that can affect the overall appearance of the gem but do not penetrate into the interior of the stone. These can include scratches, nicks, or other marks that occur during the cutting and polishing process.

In contrast, inclusions refer to internal characteristics or irregularities found within the gemstone itself, which are typically created during the formation process and can affect the overall clarity and visual appeal of the stone. Flaws and defects are broader terms that can encompass both surface and internal issues, but blemishes specifically highlight those imperfections that lie on the exterior. Thus, the precise designation of such surface irregularities as blemishes helps in accurately categorizing the types of imperfections encountered in gemstones.