Reading a diamond grading report: seven lines to check

Diamonds from 0.30 ct at Kim Bảo Minh Châu come with a report from an independent laboratory. Reports carry many fields; these seven matter most.

1. Report number

The stone's unique ID. Many labs laser-inscribe it on the girdle. Ask staff to show it under a loupe, match it to the paper and look it up on the lab's website.

2. Shape and cutting style

For example round brilliant, oval, pear. Shape affects price and brilliance.

3. Measurements

In millimetres, for example 6.45 × 6.48 × 3.98 mm. Two stones of equal weight can face up at different sizes; a stone cut too deep looks smaller.

4. Carat weight

1 carat equals 0.2 g. Prices jump at round weights such as 0.50 ct and 1.00 ct.

5. Colour grade

D (colourless) to Z (light yellow). D to F are colourless, G to J near-colourless. Colour shows more in white gold or platinum than in yellow gold.

6. Clarity

7. Cut grade

For rounds: Excellent, Very Good, Good, Fair, Poor. Cut drives sparkle more than colour or clarity. It is accompanied by polish, symmetry and fluorescence.

Buying at KBMC

• Stone prices are listed per stone, matched to the report, and shown on the tag and invoice.
• The report number is stored on the piece's record and linked to the ring's laser code.
• On buy-back, the stone is valued at the published rate of the original invoice price; stones with their report and a matching inscription count in full. See the Buy-back commitment.