Diamond Guide
Everything you need to understand a diamond:
From the four characteristics that define its quality, to why natural always matters.
The Four Cs
The universal language of diamonds. Cut, Colour, Clarity and Carat: four characteristics that determine every stone's quality, rarity and value.
Cut: The Master of Light
Cut is the only C created entirely by human hands, and it is the single most important factor in a diamond's beauty. A perfectly cut diamond will reflect light internally from facet to facet and return it through the top, creating that signature brilliance.
Poor cut, regardless of colour or clarity, produces a dull, lifeless stone. At SRS, we supply top make quality only. This is non-negotiable. A perfectly cut round brilliant diamond can internally reflect up to 83% of the light entering the stone; the remaining 17% is reflected off the surface. Every reduction in cut quality directly diminishes that internal reflection, producing a visibly less brilliant result.
GIA Cut Grades
Did you know? The finest cut round brilliant diamond internally reflects approximately 83% of all light entering the stone. The remaining 17% is reflected off the surface. Stones cut to lesser standards return progressively less light, resulting in diminished brilliance and fire.
GIA Colour Scale: International Standard
The GIA colour scale is the global standard used by every major diamond laboratory worldwide. SRS Diamonds sources exclusively to this standard.
SRS Minimum: G Colour
Colour: Purity of the Stone
The GIA colour scale runs from D (perfectly colourless) to Z (visibly yellow or brown). The less colour a diamond has, the rarer and more valuable it is.
G is the lowest colour grade that appears colourless to the naked eye when set in jewellery. Below G, subtle yellow begins to show, particularly in larger stones and step cuts. This is why G is our floor, not a ceiling. We never go below it.
D, E, F grades are considered colourless. G, H are near-colourless. SRS supplies G and above, meaning every stone we sell appears white and bright to the human eye.
Clarity: Nature's Fingerprint
Almost all diamonds contain natural inclusions, which are tiny internal characteristics formed during their creation billions of years ago. Clarity measures how many inclusions are present, and how visible they are.
SRS supplies IF (Internally Flawless) through to SI2 (Slightly Included). In this range, inclusions are either invisible to the naked eye, or visible only under 10× magnification.
Full GIA Clarity Scale
SRS supplies IF through SI2. FL and I1–I3 are outside our standard range.
Custom Clarity Sourcing
We go beyond standard grading. A client may require a VS2 stone where no black crystal is visible on the table. We source and verify to exactly that specification.
This level of precision sourcing is what we do. Your specification is our brief, not a complication.
Weight Ranges We Supply
Specific weights to 3 decimal places available on request
Carat: Size and Weight
Carat is the measure of a diamond's weight. The word derives from the carob bean, the seed of the locust tree, which ancient gem traders used as counterweights due to its remarkably consistent weight. Over centuries of international trade, the standard was formalised: the carob bean's average weight of 0.197 grams was rounded to exactly 0.2 grams, which remains the definition of one carat to this day. It is often the first characteristic buyers specify, but it works in combination with cut and clarity to determine visual size.
At SRS, we source to exacting weight specifications. If a client requires a specific stone weight to the thousandth of a carat. For example, 0.503ct. We source and match to that precision.
This level of specification matching is standard practice for us. It ensures perfectly matched sets, consistent productions runs, and exact per-stone economics for manufacturers.
Round Diamond Parcel Grades
Round diamonds traded in parcels are categorised by sieve — calibrated plates through which stones fall by diameter, separating them by size and weight. Understanding these grades is fundamental to reading the diamond trade.
Natural vs Lab-Grown
Two stones that look identical. One took 3 billion years to form. The other took 3 weeks. The difference matters more than the industry lets on.
Formed by the Earth.
Over Billions of Years.
- ◆Formed 100 to 150 miles underground over 1 to 3 billion years under extreme heat and pressure
- ◆Finite supply. No new natural diamonds are being created on a human timescale
- ◆Retains long-term value. Historically appreciates or holds value over time
- ◆Each stone is unique. No two natural diamonds are identical
- ◆The geological rarity is part of the diamond's story, and its value to the person who wears it
"A natural diamond is not just a stone. It is a record of the Earth's history, compressed into something you can hold."
Manufactured in a
Factory. In Weeks.
- ○Created in a laboratory using high pressure or chemical vapour deposition in 2–4 weeks
- ○Unlimited supply. Production can be scaled indefinitely, driving prices down consistently
- ○Declining resale value. Lab diamond prices have fallen significantly year on year
- ○Chemically identical to natural, but carries no geological provenance or rarity
- ○No inherent story. Manufactured to order, interchangeable, disposable
SRS Diamonds does not supply lab-grown stones. We deal exclusively in natural, polished diamonds.
SRS supplies natural diamonds. Only.
Every stone we source, evaluate and supply is a natural, polished diamond, with all the rarity, provenance and value that entails.
Diamond Certification
Certified diamonds have been assessed by an independent gemological laboratory. The certificate is a permanent, objective record of that stone's exact characteristics.
The world standard in diamond grading. The most trusted and widely recognised certificate globally.
Visit GIA →Europe's leading diamond laboratory, based in Antwerp, our home city. HRD certificates are widely accepted across European jewellery markets.
Visit HRD →A globally recognised laboratory with a strong presence in Asian and North American markets. IGI certified stones are accepted by major international buyers.
Visit IGI →