IGI Certified Diamond Prices in United Kingdom

IGI-certified diamond pricing in United Kingdom, refreshed daily across more than one hundred retailers. Current GBP medians for natural and lab-grown listings, plus the per-carat premium versus the market baseline.

Last updated 31 October 2026 · Based on 25,549,692 active IGI-certified listings

Total listings
25,549,692
Natural median (GBP)
£1,350/ct
Lab-grown median (GBP)
£360/ct
Premium vs baseline
+109.9%

Is IGI Certification the Right Choice?

The International Gemological Institute (IGI) is the largest grader of lab-grown diamonds globally and a major player in natural diamond grading, particularly in the European and Indian markets. IGI certificates are widely accepted by jewellers, banks, and insurance companies. Functionally interchangeable with GIA for most practical purposes, and significantly more common in lab-grown inventory.

Stones carrying a IGI certificate trade at about a 109.9% premium over the market baseline in our data. That's the 'GIA effect' at work. Buyers trust the grading rigour and are willing to pay for it. If you're going to resell the stone or want the most conservative paper trail, the premium is real and worth considering.

IGI certificates cover 25,549,692 listings in our database, and the overwhelming majority are lab-grown, 23,921,938 lab stones vs 1,627,654 natural. This is the lab-grown industry's dominant certificate: efficient, affordable, and comfortable with the volumes of lab output hitting the market.

Most of the IGI-certified inventory we track is in ROUND (8,541,420 listings). Consistent with round being the default for engagement-ring buyers. If you're shopping fancy shapes, selection thins out quickly across every lab; widening your search to two or more certificate issuers often doubles the available inventory.

For lab-grown diamonds IGI is the default choice. Cheaper, faster, and with no discount on quality of grading. For natural diamonds IGI is well-accepted in most markets but traditionally has graded slightly softer on colour and clarity than GIA, which is priced into the market. A GIA certificate on a natural stone will still command a small premium on resale.

Breakdown by Shape

ShapeOriginListingsMedian (GBP)
ROUNDlab grown8,541,420£328/ct
OVALlab grown3,627,347£382/ct
PEARlab grown2,288,861£370/ct
EMERALDlab grown2,097,546£358/ct
MARQUISElab grown1,753,246£401/ct
RADIANTlab grown1,659,586£380/ct
CUSHIONlab grown1,506,227£423/ct
PRINCESSlab grown1,190,548£365/ct
ROUNDnatural1,146,640£1,306/ct
HEARTlab grown681,683£324/ct
ASSCHERlab grown421,523£379/ct
PEARnatural146,990£1,471/ct
OTHERlab grown123,108£514/ct
OVALnatural115,846£1,484/ct
EMERALDnatural68,220£1,463/ct
MARQUISEnatural53,510£1,360/ct
PRINCESSnatural32,819£1,682/ct
HEARTnatural31,096£1,568/ct
TRILLIONlab grown17,681£454/ct
CUSHIONnatural16,363£1,245/ct

Breakdown by Carat

CaratOriginListingsMedian (GBP)
0.5-0.99ctnatural546,787£1,169/ct
0.5-0.99ctlab grown2,116,068£410/ct
0.5-0.99ctunknown7£867/ct
1.0-1.49ctnatural273,794£1,758/ct
1.0-1.49ctlab grown5,028,117£335/ct
1.0-1.49ctunknown5£2,246/ct
1.5-1.99ctnatural157,509£2,314/ct
1.5-1.99ctlab grown4,272,261£341/ct
2.0-2.99ctnatural82,153£3,414/ct
2.0-2.99ctlab grown5,252,604£372/ct
2.0-2.99ctunknown1£2,614/ct
3.0ct+natural38,791£5,913/ct
3.0ct+lab grown6,362,394£353/ct
3.0ct+unknown1£206/ct
under-0.5ctnatural528,620£1,053/ct
under-0.5ctlab grown890,494£441/ct
under-0.5ctunknown86£944/ct
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