Home/Diamond Guide
Before you buy
Everything we would tell our own family
The 4Cs in plain language, the shapes that suit which hand, what a certificate actually proves, and how to keep a stone bright for forty years.
The four Cs
Four measurements decide
almost all the price
Learn them in ten minutes and you will never be sold the wrong stone — here or anywhere else.
1 · Cut — the one that matters most
Cut is not the shape. It is how well the stone's proportions, symmetry and polish were executed, and it is the only C decided by a person rather than by geology. Get it right and light entering the crown bounces off the pavilion facets and comes straight back at you. Get it wrong and light leaks out of the bottom, leaving a large, dull, expensive stone.
If you compromise on any C, do not let it be this one.
2 · Colour — how little there is
Diamonds are graded D (completely colourless) through to Z (noticeably tinted). The difference between neighbouring grades is invisible face-up to almost everyone; the difference in price is not. Setting metal matters too — a warm H or I disappears in yellow gold, while platinum shows every degree of tint, so a colourless D–F earns its premium there.
Our tip: G–H in white metal, I–J in yellow gold. The saving is real, the difference is not.
3 · Clarity — what is inside
Nearly every natural diamond carries inclusions — crystals, feathers, clouds — formed under the ground. Clarity grades how many, how big and how visible they are under 10× magnification. What you actually care about is whether the stone is eye-clean: invisible at normal reading distance. From VS2 upward, almost every stone is.
Paying for IF over VS1 buys you a certificate line, not a visible difference.
4 · Carat — weight, not size
One carat is 200 milligrams. Because price per carat jumps at the round numbers the trade cares about, a 0.92 ct and a 1.00 ct can look identical on a finger while the second costs noticeably more. Spread — how wide the stone looks face-up — depends as much on cut and shape as on weight. Ovals, marquises and pears all read larger per carat than a round.
Diameters shown for a well-cut round brilliant.
Shapes
Eight cuts, eight personalities
Shape is taste, not quality. But some shapes flatter a short finger, some hide colour better, and some cost 20% less for the same weight.
Certification
What the paper
actually proves
A grading report is not a valuation and not a guarantee of price. It is an independent laboratory saying: this specific stone, with these measurements, has this cut, colour and clarity. That is what makes it comparable — and re-sellable.
GIA (Gemological Institute of America) set the grading scale the whole trade uses and grades most strictly. IGI grades to a closely comparable standard, faster and at lower cost, and dominates certification for lab-grown stones. BIS is different again — it hallmarks the gold, not the diamond, certifying purity in karats.
Three things to check on any report before you pay: the laser inscription number on the girdle matches the certificate, the measurements match the stone in front of you, and the report is dated within the last few years.
Bring a certificate in to check
Natural or lab-grown
The same material,
two different purchases
Natural diamonds
Formed over a billion years, finite in supply, and the only version that holds meaningful resale and exchange value. This is what we recommend for engagement rings, bridal sets and anything intended to pass down.
Priced by rarity. Certified individually above 0.30 ct.
Lab-grown diamonds
Chemically identical, optically identical, grown in weeks rather than aeons. Typically 60–80% less for the same size and grade — excellent for statement earrings, tennis bracelets and pieces where size is the point.
Resale value is low and still falling. We label every lab-grown stone as such, on the tag and on the bill.
Care
Keeping a stone bright
Wash it monthly
Warm water, a drop of dish soap, five minutes to soak, then a soft toothbrush behind the stone where the film collects. Rinse and pat dry.
Take it off first
Before the gym, the garden, the kitchen and the swimming pool. Chlorine attacks the alloys in gold settings; a knock against tile chips a girdle.
Store pieces apart
A diamond scratches every other gem and every other diamond. Separate pouches, or the fitted case your piece came in.
Check the prongs twice a year
Prongs wear. Bring the piece in and we will check, tighten, clean and re-polish it free — an appointment takes twenty minutes.
Questions
Asked at the counter
Is a certified diamond really worth the extra cost?
Yes — because the certificate is what makes the stone re-sellable and insurable. An uncertified diamond is worth whatever the next buyer says it is worth. A GIA or IGI report fixes the colour, clarity, cut and measurements independently, so both sides are arguing from the same page.
GIA or IGI — which certificate should I insist on?
GIA is the strictest and most widely recognised, and we recommend it for anything above one carat. IGI grades to a very similar standard and is faster and less expensive, which makes it sensible for melee and smaller centre stones. We stock both and will tell you which lab graded any stone before you ask.
What is the difference between natural and lab-grown diamonds?
Chemically and optically they are the same material; the difference is origin and price. A lab-grown stone typically costs 60–80% less for the same size and quality, but it does not hold value the way a natural stone does. We sell both, we label both clearly, and we will never let a lab-grown stone leave here described as anything else.
How much should I actually spend on an engagement ring?
There is no rule, whatever the advertising says. What matters more is the balance: a well-cut 0.70 ct in G/VS2 will out-sparkle a poorly cut 1.00 ct in the same budget. Tell us the number you are comfortable with and we will show you the best stone that fits it.
Do you buy back or exchange old jewellery?
Yes. Diamond jewellery bought from us is exchanged at full diamond value against a new piece. Gold is exchanged at the day's rate against the hallmarked weight. Pieces bought elsewhere are assessed on the counter, in front of you, with the weight and rate written down before anything is agreed.
How often should diamond jewellery be cleaned?
Professionally every six months — sooner if you cook or garden in your rings. Body oil and soap film sit under the stone and kill the return of light long before anything looks visibly dirty. Cleaning and prong-checks are free here, for life, whether or not you bought the piece from us.
Next step
Bring your idea, or just
come and look
Appointments are free and unhurried. We will set out a tray, hand you a loupe, and explain every certificate before anything is decided.