When evaluating LED wash lights, prioritize high-efficiency LEDs (such as Cree or Osram chips) to ensure color consistency and longevity. Key metrics include the Beam Angle (typically 25° to 60° for washing), Luminous Efficacy (aim for >100 lm/W), and Color Rendering Index (CRI), where a CRI >80 is essential for accurate color reproduction in architectural or stage settings. Additionally, verify the IP Rating; for outdoor applications, an IP65 or IP66 rating is mandatory to ensure dust-tightness and protection against heavy seas or powerful jets of water.