Diamonds are graded on a color scale from D (completely colorless ... comes with a certification from a reputable grading laboratory, such as the GIA or AGS. These certifications provide an ...

The lightbulbs are identical so every grade can be on the exact same scale. “The color differences are so fine, there’s no room for any variation.” The GIA color scale runs from D to Z ...

Instead, beginning later this year, lab-grown diamonds submitted to GIA will receive simplified descriptors—categorised broadly as either “premium” or “standard”—or no grade at all if ...