• +44 (0)207 491 4777
  • contact@gcslab.co.uk
  • 30 New Bond Street, London W1S 2RN



Full 4Cs assessment with a plotted Carat, Colour, Clarity, Cut quality grading.

This quality determination follows the CIBJO rules, edited in the Diamond book. Stones under 0.30ct are not graded. Diagram, face-up diamond image on the card. For loose, D-to-Z color diamonds only, weighing 0.15 carats or more.

Diamond Type Analysis

Determination of diamond type – Ia, Ib, IIa or IIb. Results delivered on the report. Variety of testing services to determine diamond authenticity, natural vs. synthetic, natural vs. treated, or identify specific treatments.

Colored Diamond Grading Report

Full quality assessment, color grade and clarity plot. Identifies natural vs. treated color. In order to determine whether a diamond is of natural or artificial colour, the following investigations are routinely performed on loose stones:
Observation with a binocular microscope in dark field, transmitted light, polarized light, and immersion.
FTIR spectroscopy to determine the type of diamond (type IaA, IaA/B, IaB, Ib, IIa, IIb). UV-visible-near-infrared spectroscopy of the diamond, Raman Photoluminescence spectroscopy of the diamond.