The newspaper test: place the diamond face-down on newspaper text. If you can read the text through the stone, the cut is too deep or the light return is poor. I did this casually four months after buying. I could read the text. Clearly. My stone: GIA 1ct G-VS2, cut grade: Excellent. On paper, this is a well-cut stone. Here is the problem: GIA Excellent covers a range. The acceptable Excellent range for depth is 59–62.3%. My stone was 62.1% — technically Excellent, physically at the deep end of the range where light leakage through the pavilion begins. What the certificate says vs what matters: GIA grades: Excellent, Very Good, Good, Fair, Poor. What the certificate does NOT tell you: • Table %: should be 53–58% for maximum fire • Crown angle: should be 34–35° for optimal light return • Pavilion angle: should be 40.6–41° — this is the single most important number • Crown height: 15–17% is ideal My stone: pavilion angle 41.6°. That is the cause of the newspaper test result. Light that should reflect back through the table is leaking out the bottom. What I do differently now: • I filter by pavilion angle 40.6–41.0° before looking at anything else • I use Holloway Cut Adviser (free online tool) to score any stone before buying • GIA Excellent is a minimum bar, not a guarantee of performance If you are shopping right now: request the full proportion data beyond what the basic certificate shows. A 0.4° pavilion angle difference is invisible on paper and visible in your ring.