Diamond Buying Guide
Everything you need to know before choosing your diamond — explained clearly by our London jewellers.
Hallmarked Gold
All our gold pieces are assayed and hallmarked by 9 Jewels Ltd — your guarantee of genuine precious metal content.
Diamond Certification
Coming soonNot all stones automatically include a grading report. GIA or IGI certification will be available as an optional add-on at checkout — ask us in the meantime.
Cut — The Most Important C
Cut determines how well a diamond reflects light — its brilliance, fire, and scintillation. A poorly cut diamond will appear dull regardless of its colour or clarity. Always prioritise cut above the other Cs.
Excellent
Maximum light performance — recommended
Very Good
Slightly less sparkle — good value
Good
Noticeably less brilliant
Cut grades by shape
Round Brilliant
The most popular cut. Maximises light reflection and sparkle. A classic choice for engagement rings.
Princess Cut
Square with sharp corners. Modern and brilliant, second only to round in popularity.
Oval Cut
Elongated shape that makes fingers appear longer. High brilliance similar to round.
Cushion Cut
Rounded corners with a vintage feel. Warm, romantic sparkle suited to halo settings.
Emerald Cut
Step-cut facets create a hall-of-mirrors effect. Sophisticated and understated.
Pear Cut
Teardrop shape combining round and marquise. Flattering and distinctive.
Clarity — What's Inside
Clarity refers to the presence of natural inclusions and blemishes. Most inclusions are microscopic and invisible to the naked eye. You do not need a flawless stone for it to look perfect in a ring.
FL / IF
Flawless / Internally Flawless
No inclusions visible under 10× magnification. Extremely rare.
VVS1 / VVS2
Very Very Slightly Included
Inclusions so tiny they are extremely difficult for a skilled grader to see.
VS1 / VS2
Very Slightly Included
Minor inclusions invisible to the naked eye. Excellent value and a popular choice for centre stones.
RecommendedSI1 / SI2
Slightly Included
Inclusions noticeable under magnification; usually eye-clean at SI1.
I1 / I2 / I3
Included
Inclusions visible to the naked eye. Not recommended for centre stones.
Colour — How White Is White?
Diamond colour is graded on a scale from D (colourless) to Z (light yellow). For most engagement rings, G–J offers the best balance of quality and value — the stone will look white face-up.
D–F
Colourless
The most prized and rare. No detectable colour even to trained eyes.
G–J
Near Colourless
Colour only detectable when compared to higher grades. Excellent value.
Best valueK–M
Faint
Slight warmth detectable face-up. Better suited to yellow or rose gold settings.
N–Z
Very Light to Light
Noticeable colour. Generally not recommended for engagement rings.
Carat — Weight, Not Size
Carat is the unit of weight for a diamond (1ct = 0.2g). Heavier diamonds are rarer and command a premium. However, carat weight alone does not determine how large a diamond looks — cut, shape, and mounting all affect perceived size.
Approximate face-up diameter (round brilliant)
0.25ct
~4.1mm
0.50ct
~5.2mm
0.75ct
~5.9mm
1.00ct
~6.5mm
1.50ct
~7.4mm
2.00ct
~8.2mm
2.50ct
~8.8mm
3.00ct
~9.4mm
Natural vs Lab-Grown Diamonds
Natural Diamond
- → Formed over billions of years deep in the earth
- → Rare, finite supply — traditionally holds value
- → Ethically sourced; GIA/IGI certification available on request
- → Higher price per carat
Lab-Grown Diamond
- → Chemically and physically identical to natural diamonds
- → More sustainable and eco-conscious choice
- → IGI certification available on request
- → Significantly lower price for the same visual quality
Need Help Choosing?
Our jewellery consultants offer free, no-obligation advice on diamond selection. Tell us your budget and preferences and we'll guide you to the ideal stone.