UK Lab-Grown Diamond Price Index

Three retailers. 2,706 listings. G VS1 Round Excellent IGI.

• The price difference is not a quality difference. It is a retailer difference. At 2ct, the gap reaches £382 on a single stone.
• Diamond Labs ranked cheapest at all three weight tiers.
• What UK buyers assume is a cross-border premium is VAT and exchange rate, not markup. Brilliant Earth UK is excluded from this index: their GBP prices are derived from a USD conversion formula, not independently set for the UK market.
• We audited six UK retailers. Three qualified. London-based Queensmith passed structural eligibility but carries zero G-color lab-grown diamonds. Their inventory is exclusively D, E, and F color, confirmed via live API across all carat bands. A three-retailer result at G VS1 is not a methodology gap. It is the market.
• All prices inc-VAT (20% UK VAT included). Ex-VAT figures are in the methodology section.
• The UK index tracks G VS1, the highest-volume lab-grown specification across UK retailers. The Rings.com US index uses E VS1. Not directly comparable. E commands a color premium over G.

Scope. This index tracks listed retail prices (not transaction prices) across major UK online lab-grown diamond retailers. The May 2026 inaugural edition covers 2,706 benchmark-matching lab-grown diamond listings across three retailers. All prices are in GBP, inclusive of 20% UK VAT (inc-VAT). Data was collected in May 2026.

Retailer panel. This edition tracks three retailers: Diamond Labs, 77 Diamonds, and Quality Diamonds. Eight retailers were evaluated in May 2026. Two (Brilliant Earth UK and James Allen) were screened out before formal audit: both price in GBP via USD conversion rather than independently setting UK prices. Six retailers proceeded to formal audit against four criteria: (1) live filterable inventory API with no credentials required, (2) publicly visible per-listing GBP pricing, (3) IGI certification as a filterable and per-listing attribute, and (4) minimum 30 qualifying listings per carat cell. Three qualified. Three were excluded; exclusion reasons are documented in the Excluded retailers note below. The panel is fixed and disclosed for comparability. Any additions, removals, or reclassifications will be explicitly noted in that month's report.

Excluded retailers. Queensmith (queensmith.co.uk) passed structural eligibility criteria but stocks exclusively D, E, and F color lab-grown diamonds: a live API query in May 2026 found zero G-color listings across all three benchmark carat bands, consistent with their premium-positioning sourcing standard. Purely Diamonds (purelydiamonds.co.uk) and Angelic Diamonds (angelicdiamonds.com) are finished jewelry retailers with no loose diamond search inventory.

Price inputs. Prices are the publicly visible list price at the time of data collection, inclusive of 20% UK VAT. Ex-VAT medians: Diamond Labs 1ct £200/ct, 1.5ct £251/ct, 2ct £310/ct. 77 Diamonds 1ct £254/ct, 1.5ct £371/ct, 2ct £469/ct. Quality Diamonds 1ct £304/ct, 1.5ct £367/ct, 2ct £438/ct.

Benchmark specification. The benchmark specification is G color, VS1 clarity, round brilliant, Excellent cut, IGI-certified. G color was chosen because it is the highest-volume specification available with consistent depth across all three tracked UK retailers. Three weight cells are tracked: 1ct (0.95-1.05ct), 1.5ct (1.45-1.55ct), and 2ct (1.95-2.05ct). Note: the Rings.com US price index uses E color rather than G color. E is a higher color grade and commands a price premium. Cross-market comparisons between the US and UK indices should account for this grade difference.

Statistical method. Each published figure is the median total stone price across all qualifying listings within that cell. A minimum of 30 qualifying listings is required for publication. All cells in this edition meet that threshold.

Data sourcing. The UK index is built from live API queries against each retailer's product inventory backend. All three APIs are public-facing endpoints that power the retailers' own consumer-facing search pages. No credentials, scraper accounts, or private API keys were used.

Market concentration. The UK online lab-grown market is tracked here across three retailers (Diamond Labs, 77 Diamonds, and Quality Diamonds): the primary UK-accessible online retailers with independently-priced GBP inventory and sufficient benchmark-matching stock to produce stable medians across all three carat tiers. The narrower price spread observed in the UK index (approximately 1.5x at each carat tier, versus 4x in the US index) is consistent with this market structure.

Independence. Rings.com receives no compensation from the retailers included in this index for inclusion or ranking, and no retailer has any editorial control over the methodology or results. This index reflects public list prices only; individual purchase prices may differ due to custom configurations, time-sensitive promotions, or VAT treatment at purchase.