Quality evaluation of rough turquoise depends on three primary factors: hardness, color, and matrix. High-grade rough should have a Mohs hardness of 5 to 6; chalky or soft stones often require stabilization and are less valuable. Look for vibrant sky blue or deep teal hues, as pale or greenish tints may indicate lower copper content or higher iron levels. Additionally, assess the matrix (host rock) patterns—while 'spiderweb' patterns are highly prized in the jewelry market, excessive or crumbly matrix can reduce the usable yield during cutting and polishing.