Which of the following tools is most suitable for examining skin texture closely?

The loupe is specifically designed for magnifying and closely examining the skin's texture, making it the most suitable tool for this purpose. A loupe typically has a built-in light and can magnify the skin, allowing estheticians to identify fine details such as pores, blemishes, and texture irregularities that might not be visible to the naked eye.

In contrast, other tools serve different functions. A microdermabrasion tool is aimed at exfoliating the skin's surface and improving its overall appearance rather than examining it. A mirror can provide a reflection but lacks the magnification needed for a detailed analysis of skin texture. A pore extractor is used for removing impurities and comedones from the skin, not for examination. Thus, the loupe stands out as the ideal choice for closely examining skin texture due to its specific design for magnification and analysis.