IGI Certified Diamond Prices in New Zealand

IGI-certified diamond pricing in New Zealand, refreshed daily across more than one hundred retailers. Live NZD medians for natural and lab-grown listings, plus the per-carat premium versus the market baseline.

Last updated 14 September 2026 · Based on 18,475,327 active IGI-certified listings

Total listings
18,475,327
Natural median (NZD)
$2,924/ct
Lab-grown median (NZD)
$816/ct
Premium vs baseline
+90.5%

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 90.5% 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 18,475,327 listings in our database, and the overwhelming majority are lab-grown, 17,258,525 lab stones vs 1,216,690 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 (6,635,553 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 (NZD)
ROUNDlab grown6,635,553$758/ct
OVALlab grown2,726,726$858/ct
PEARlab grown1,743,765$840/ct
EMERALDlab grown1,263,806$815/ct
CUSHIONlab grown1,139,260$868/ct
MARQUISElab grown1,129,783$924/ct
RADIANTlab grown1,087,769$884/ct
ROUNDnatural878,439$2,824/ct
PRINCESSlab grown818,479$858/ct
HEARTlab grown384,033$773/ct
ASSCHERlab grown235,388$846/ct
PEARnatural101,893$3,023/ct
OVALnatural81,006$3,373/ct
OTHERlab grown75,013$1,303/ct
EMERALDnatural55,035$3,221/ct
MARQUISEnatural32,525$2,966/ct
PRINCESSnatural26,068$3,591/ct
HEARTnatural21,399$3,140/ct
TRILLIONlab grown13,033$1,162/ct
CUSHIONnatural8,544$3,275/ct

Breakdown by Carat

CaratOriginListingsMedian (NZD)
0.5-0.99ctnatural408,195$2,632/ct
0.5-0.99ctlab grown1,842,312$965/ct
0.5-0.99ctunknown8$1,874/ct
1.0-1.49ctnatural201,877$3,923/ct
1.0-1.49ctlab grown4,210,390$750/ct
1.0-1.49ctunknown5$5,215/ct
1.5-1.99ctnatural109,137$5,061/ct
1.5-1.99ctlab grown3,268,933$749/ct
1.5-1.99ctunknown2$3,738/ct
2.0-2.99ctnatural59,320$7,630/ct
2.0-2.99ctlab grown3,531,500$820/ct
2.0-2.99ctunknown5$728/ct
3.0ct+natural27,818$13,418/ct
3.0ct+lab grown3,696,990$803/ct
3.0ct+unknown1$459/ct
under-0.5ctnatural410,343$2,369/ct
under-0.5ctlab grown708,548$1,122/ct
under-0.5ctunknown91$2,207/ct
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