Radiant|Lab Grown|IGI

12.78ct F SI1 Radiant Lab Grown Diamond

ID • F/SI1 • IGI LG591336712

Shape and cutting style on the report: Cut cornered rectangular modified brilliant

Certificate IGI LG591336712

Diamond specifications and retailer prices

From £1,137 GBP
As of November 2, 2026
Save £1,516 GBP (57%) vs most expensive(unlock to see where)
13 retailers carry this diamond
Most expensive: £8,168 GBP at Adiamor · As of November 2, 2026
View at Adiamor

About this 12.78ct lab-grown radiant diamond

This 12.78ct lab-grown radiant sits in the over five carat band, graded F colour (colourless) and SI1 clarity (slightly-included), with a top-tier cut grade and certified by IGI LG591336712 or 591336712. Listed at 13 retailers as of November 1, 2026, with a 133% spread between the cheapest and most expensive listing. That is exactly the kind of price-discovery gap Carat Hunter was built to surface. 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

12.78
Carat
F
Colour
SI1
Clarity
Ideal
Cut

Specifications

CutIdeal
PolishExcellent
SymmetryExcellent
FluorescenceNone
Crown angle44.8°
Pavilion angle34°
OriginLab Grown
Grading LabIGI
CertificateIGI LG591336712
Dimensions16.82 × 11.37 × 7.51 mm
L/W Ratio1.48
Cert comments
This Laboratory Grown Diamond was created by Chemical Vapor Deposition (CVD) growth process and may include post-growth treatment Type IIa
Top View
16.82 mm11.37 mm12.78 ctF / SI1
OriginLab Grown
CutIdeal
PolishExcellent
SymmetryExcellent
FluorescenceNone
CertificateIGI LG591336712
Side View
Table 65.0%Crown 44.8°Girdle: Slightly ThickPavilion 34°Culet: NoneDepth 66.1%

Caratlytics Score

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A
Excellent
Excellent quality and great value
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Price History

Last verified: Nov 2
Current: £8,168 GBP|Low: £1,137 GBP|High: £17,079 GBP|Avg: £4,732 GBP|-52.2%
Adiamor
Retailer 2
Retailer 3
Retailer 4
Retailer 5
Retailer 6
Retailer 7
Retailer 8
Retailer 9
Retailer 10
Retailer 11
Retailer 12
Retailer 13
Retailer 14
Retailer 15
Retailer 16
November 2, 2026
Retailer 2£1,137 GBP
Retailer 6£1,220 GBP
Retailer 5£1,328 GBP
Retailer 13£1,415 GBP
Retailer 14£1,541 GBP
Retailer 16£1,662 GBP
Retailer 15£1,865 GBP
Retailer 9£1,989 GBP
Retailer 10£2,226 GBP
Retailer 11£2,247 GBP
Retailer 12£2,440 GBP
Retailer 3£2,652 GBP
Retailer 4£4,541 GBP
Adiamor£8,168 GBP
Retailer 7£15,300 GBP
Retailer 8£15,337 GBP

7 data points across 16 retailers

13 retailers£1,137 GBP to £2,652 GBP

A
Cheapest Retailer
-
£1,137 GBP
A
Retailer 2
-
£1,220 GBP
$1,635 USD
View
A
Retailer 3
-
£1,328 GBP
$1,779 USD
View
A
Retailer 4
-
£1,415 GBP
$1,896 USD
View
A
Retailer 5
-
£1,541 GBP
$2,065 USD
View
B+
Retailer 6
-
£1,662 GBP
HK$17,400 HKD
View
B+
Retailer 7
-
£1,865 GBP
$2,499 USD
View
B+
Retailer 8
-
£1,989 GBP
View
B+
Retailer 9
-
£2,226 GBP
$2,982 USD
View
B
Retailer 10
-
£2,247 GBP
€2,867 EUR
View
B+
Retailer 11
-
£2,440 GBP
$3,269 USD
View
B
Retailer 12
-
£2,652 GBP
$3,554 USD
View
Most Expensive
Adiamor
D-82832577 · Nov 2
£8,168 GBP
$10,944 USD
View
Price under review
12 more retailers have this diamond
Prices start from £1,137 GBPSave up to £1,516 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
12.78ct Radiant
£1,137 GBP