When sourcing low iron glass, the primary indicator of quality is Visible Light Transmittance (VLT), which should be ≥91% for standard thicknesses. The iron content must be strictly controlled, typically below 150ppm (0.015%), to eliminate the green tint characteristic of standard float glass. Buyers should also verify the Solar Heat Gain Coefficient (SHGC) if the glass is intended for architectural facades, and ensure the edge finish (polished, beveled, or arrissed) meets the aesthetic requirements of the final application.