§ METHODOLOGY

Seven variables. Three independent data sources.

The standard four Cs are necessary. They are not sufficient. Three additional variables explain most of the unexplained price variance between stones with otherwise identical certificates.

The seven variables

The inputs that move the price.

Carat

Weight in carats, to two decimal places. The single largest driver of price across the full grade range.

Cut

Excellent through Poor on the standard scale. Cut quality affects light return and clears at different prices even within the same colour and clarity grade.

Colour

D through Z. Colour grade defines the colourless range every wholesale buyer references. And the cut-offs where price tiers change.

Clarity

FL through I3. The position, size and visibility of inclusions inside the stone.

Certifying lab

Grading standards vary significantly between laboratories. The same letter grade from different labs can represent meaningfully different stones and clear at materially different prices.

Fluorescence

Affects clearing price in opposite directions depending on the stone's colour grade. Ignored by standard benchmarks.

BGM

Brown, Green or Milky characteristics not captured by the standard clarity grade. But heavily discounted by professional buyers at the wholesale counter.

The data behind the output

Three independently defensible sources.

All publicly accessible. All independent of any benchmark publisher. No proprietary opinion list is reproduced.

Source 01

Real-time wholesale asking prices

Live B2B trading platform inventory representing billions in available stones. Updated continuously and segmented by every input the model uses.

Source 02

Confidence-weighted clearing signal

Derived from the spread between real-time wholesale asking prices and the standard weekly opinion benchmark. In 2024 the live index of one-carat trades fell 23% while that opinion list only fell 13%. The widening or tightening of that ten-point spread, across carat bands and colour grades, is the leading indicator of where stones actually clear.

Source 03

Public auction realised prices

Confirmed clearing prices from major public jewellery auctions. Sotheby's, Christie's, Bonhams, Phillips. Genuine transaction outcomes from competitive bidding. The strongest single signal we have for high-value certified stones.

Built for the trade.

Clarity First is in early access across the UK and US. Request access to your market.