Why is repolishing often performed after HPHT treatment?

• A. To address surface roughness produced by high temperatures and pressures.
• B. To deepen color changes.
• C. To increase carat weight.
• D. To remove a protective coating.

Answer: (A)

Post-treatment finishing is what repolishing is about after HPHT. The high heat and pressure used in HPHT can leave tiny surface irregularities and micro-scratches on the diamond. Repolishing removes those imperfections and restores a perfectly smooth, highly reflective facet surface, which maximizes brilliance and light return. It’s about restoring surface quality so the diamond looks as good as possible after the treatment.

The other ideas don’t fit as well. HPHT changes color by altering the crystal structure, and repolishing won’t deepen color. Polishing doesn’t increase carat weight; removing material would either slightly reduce weight, not increase it. Removing a protective coating isn’t the goal of repolishing, and coatings aren’t typically the focus of post-HPHT finishing.