When sourcing lab-created gems, buyers must distinguish between synthetic gems (chemically identical to natural stones) and simulants (look-alikes like cubic zirconia). Quality is assessed using the 4Cs: Color, Clarity, Cut, and Carat weight. Ensure the supplier uses advanced growth methods such as CVD (Chemical Vapor Deposition) or HPHT (High Pressure High Temperature) for diamonds, and Hydrothermal or Flame Fusion for colored stones like emeralds and rubies. Always request refractive index (RI) and specific gravity (SG) data to confirm the material's physical properties match its natural counterpart.