Small stones. Big responsibility.

In 1999, we were the first laboratory to implement qualitative grading (clarity, colour, symmetry, polish, girdle thickness, etc.) of melee diamond batches for the Swiss fine watchmaking industry.

Diamond grading officially starts at 0.40 mm for a round brilliant — and this is precisely where our expertise begins. 

We grade and authenticate (naturality) diamonds from 0.40 mm up to 3.7 mm, covering the vast majority of melee diamonds used in fine jewellery and watchmaking. However, we have the technical means to grade and analyse diamonds smaller than 0.4 mm should they ever appear on the market.

As the image illustrates, a 0.40 mm diamond is very small. Yet it still carries value and requires rigorous, laboratory-grade verification.

Small stones. Big responsibility.
That’s where GGTL leads.