What to Check Before Buying a Diamond
You cannot compare two diamond prices until you are comparing the same four numbers. This is how to get them.
Price alone tells you nothing
Two rings that look identical can differ in price by a factor of two, and the reason is rarely visible across a counter. A stone one grade lower in cut sells for substantially less and still looks bright under a spotlight.
So before asking what something costs, establish what is being priced: carat, cut, colour, clarity. A price quoted without those four is not a price you can compare.
1 — The certificate
A single stone of 0.20 ct or more should carry a report from GIA, IGI or HRD. Without one, the grades are the seller's opinion — possibly accurate, but unverifiable.
Reports from laboratories outside those three are common and often grade generously. The same stone frequently comes back one or two grades lower at GIA. Verify the report number on the laboratory's own site; if you cannot, treat the report as absent.
2 — Centre stone weight, not total carat
"Total carat weight" adds up every stone in the piece. A 0.30 ct centre with 0.40 ct of small surrounding stones is advertised as 0.70 ct total — but a single 0.70 ct stone costs several times more than that arrangement.
Always ask: how many carats is the centre stone?
3 — Cut grade
Cut determines brilliance more than any other grade. Aim for Excellent or Very Good. A stone cut too deep or too shallow leaks light out of the side and looks dull whatever its carat weight.
This is the one grade not worth compromising on. Savings are better taken from colour and clarity.
4 — Colour and clarity, sensibly
D–F is colourless and priced accordingly. G–J is almost indistinguishable to the naked eye and is where the value sits. In a yellow or rose gold setting you can go further still, because the metal masks a faint tint.
In clarity, VS2 and above is clean to the naked eye. In the SI range what matters is where the inclusion sits — at the edge it is irrelevant, in the centre of the table it is visible.
5 — Fluorescence
The report has a line for it. None or Faint is fine. Strong fluorescence can give some stones a milky look in daylight, and those stones are noticeably cheaper — which is sometimes presented as a way to afford more carats.
If you are considering one, insist on seeing it in daylight. Some are perfectly fine; some are not.
6 — Metal and hallmark
Ask the weight of the setting and its fineness. In Turkey, 14 carat (585) and 18 carat (750) are both common in fine jewellery.
Gold must carry a hallmark. Look for it inside the band; if there is none, ask why.
7 — Rhodium hides colour for a while
White gold is plated with rhodium and looks brilliantly white when new. That plating masks a faint yellow tint in the stone. When it wears through after a few years and the metal warms towards yellow, the stone will read warmer too.
This is physics, not deception — but ask to see the stone loose, or against a white background, before deciding.
8 — Setting and prongs
How the stone is held matters as much as the stone. Prong tips should sit flush on the stone, be even in length, and the stone should not shift when you touch it.
A badly set stone falls out, and a fallen diamond is usually an uninsured loss. Ask where the setting was made and by whom.
9 — Returns, resizing and after-sales
Agree these before paying, not after. How many days for a return, in what condition, what happens with bespoke pieces, whether the first resize is charged.
Ours: 14 days on stock pieces, unworn and with the certificate intact; no returns on bespoke or engraved work; first resize free. Cleaning, rhodium plating and prong checks are free for life on anything bought from us.
10 — Pressure is the warning sign
"Today only", "another customer is waiting", "last piece". A diamond is not a departing train — a stone meeting the same specification can always be found.
If the urgency consistently comes from the other side of the counter, it is not there for your benefit. Asking for a day to think is every buyer's right, and a shop that resents it is not the shop.
Checklist
- Carats of the centre stone?
- Which laboratory issued the report, and what is the number?
- Did I verify that number on the laboratory's site?
- Cut grade — Excellent or Very Good?
- What does the fluorescence line say?
- Setting weight, fineness, hallmark present?
- Did I see the stone in daylight, beside another stone?
- Return window and resizing terms?
Anything you are unsure about? Write to us — we reply the same day — or come by the shop in the Grand Bazaar.
Ask on WhatsAppFrequently asked
What should I check before buying a diamond?
The centre stone's carat weight, which laboratory issued the certificate, and the cut grade. Without those three, a price cannot be compared to any other price.
What does total carat weight mean?
It is the combined weight of every stone in the piece. A ring with a 0.30 ct centre and 0.40 ct of small stones is sold as 0.70 ct total, but a single 0.70 ct stone costs several times more. Always ask for the centre stone's weight.
Which diamond certificate is the most reliable?
GIA grades most consistently and conservatively and is the industry reference. HRD Antwerp is the established European laboratory. IGI is widespread and is the usual reference for lab-grown stones. Reports from other laboratories often grade generously.
What cut grade should I look for?
Excellent or Very Good. Cut determines brilliance more than any other grade, and a stone cut too deep or too shallow looks dull regardless of its carat weight. Take savings from colour and clarity instead.
Is diamond fluorescence a problem?
Not necessarily. None and Faint are fine. Strong fluorescence can make some stones look milky in daylight and lowers their price — if you are considering one, insist on seeing it in daylight first.
What colour and clarity offer the best value?
G–J in colour is almost indistinguishable from colourless to the naked eye. VS2 and above is clean to the naked eye; in the SI range what matters is whether the inclusion sits at the edge or in the centre.