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1.28ct I SI1 Round Natural Diamond

EX • I/SI1 • IGI 654416426

Shape and cutting style on the report: Round brilliant

Certificate IGI 654416426

Diamond specifications and retailer prices

From £2,207 GBP
As of November 4, 2026
Save £2,124 GBP (49%) vs most expensive(unlock to see where)
14 retailers carry this diamond
Most expensive: £4,331 GBP at NZ Jewellers · As of November 5, 2026
View at NZ Jewellers

About this 1.28ct natural round diamond

This 1.28ct natural round sits in the one-and-a-quarter to one-and-a-half carat band, graded I colour (near-colourless) and SI1 clarity (slightly-included), with a top-tier cut grade and certified by IGI 654416426. Listed at 14 retailers as of November 4, 2026, with prices from £2,207 to £4,331, a £2,124 spread on the same certified stone. NZ Jewellers lists it at £4,331. SI-grade stones are eye-clean roughly 60 to 70% of the time at this carat range. Check the inclusion plot on the cert and ask the retailer for high-resolution video before buying.

The 4Cs

1.28
Carat
I
Colour
SI1
Clarity
Excellent
Cut

Specifications

CutExcellent
PolishExcellent
SymmetryExcellent
FluorescenceNone
Crown angle33.8°
Pavilion angle41.1°
OriginNatural
Grading LabIGI
CertificateIGI 654416426
Dimensions6.98 × 7.01 × 4.25 mm
L/W Ratio1.00
Girdle conditionFaceted
Culet sizePointed
Cert comments
IDEAL CUT ROUND BRILLIANT
Top View
6.98 mm7.01 mm1.28 ctI / SI1
OriginNatural
CutExcellent
PolishExcellent
SymmetryExcellent
FluorescenceNone
CertificateIGI 654416426
Side View
Table 60.0%Crown 33.8°Girdle: MED-STKPavilion 41.1°Culet: NoneDepth 60.7%

Caratlytics Score

How it works →
A
Excellent
Excellent quality and great value
Unlock full score analysis
See the detailed 0 to 100 score with Quality, Value, Certification & Market breakdown

Price History

Last verified: Nov 4
Current: £2,321 GBP|Low: £2,294 GBP|High: £4,106 GBP|Avg: £2,837 GBP|-1.7%
Retailer 1
Retailer 2
Retailer 3
Retailer 4
Retailer 5
Retailer 6
Retailer 7
November 6, 2026
Retailer 6£2,294 GBP
Retailer 1£2,321 GBP
Retailer 7£2,581 GBP
Retailer 2£2,603 GBP
Retailer 3£2,725 GBP
Retailer 4£3,034 GBP
Retailer 5£4,046 GBP

39 data points across 7 retailers

14 retailers£2,207 GBP to £4,331 GBP

A
Cheapest Retailer
-
£2,207 GBP
A
Retailer 2
-
£2,294 GBP
View
Final sale: no returns
A
Retailer 3
-
£2,321 GBP
View
A
Retailer 4
-
£2,402 GBP
View
A
Retailer 5
-
£2,486 GBP
View
Retailer 6
-
£2,486 GBP
View
Price last confirmed 8 days ago
B+
Retailer 7
-
£2,581 GBP
View
B+
Retailer 8
-
£2,593 GBP
View
A
Retailer 9
-
£2,603 GBP
View
B+
Retailer 10
-
£2,725 GBP
View
B+
Retailer 11
-
£2,868 GBP
View
B+
Retailer 12
-
£3,034 GBP
View
B
Retailer 13
-
£4,046 GBP
View
Most Expensive
B
NZ Jewellers
8092b639-6918-494c-8177-29875da9e610 · Nov 5
£4,331 GBP
$5,797 USD
View
13 more retailers have this diamond
Prices start from £2,207 GBPSave up to £2,124 GBP

Carat Hunter is not affiliated with, endorsed by, or sponsored by any retailer listed. Retailer information is from publicly available sources and may not be current. Verify details directly with the retailer before purchasing. Return terms as we hold them. Check the retailer's own returns page before you buy.

A
1.28ct Round
£2,207 GBP