1. Decide the purpose
Engagement ring, loose stone, upgrade, earrings or investment-style purchase. The purpose changes how much weight to give to size, colour, clarity and certificate.
Practical buyer guide
How To Buy A Diamond — A Practical Guide
A plain-English guide to the 4Cs, certification, natural versus lab-grown diamonds, certificates, pricing and how to view stones with David before you buy.
Recent public Google reviews from Diagem clients
What Our Clients Say ↓
Home / Diamond Buying Guide
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Buy the diamond, not the sales story.
A diamond decision becomes much easier when you separate beauty, certificate, price and purpose. David's advice is simple: first understand what you are looking at, then compare stones like-for-like before you commit.
2. Set a real budget
A useful budget is a range, not a single number. It lets David show the trade-offs between natural and lab-grown stones, size and grade.
3. Compare certificates
Never compare diamonds by size alone. Two 1ct diamonds can differ dramatically in cut, colour, clarity, fluorescence and value.
4. View before paying
Whenever possible, inspect shortlisted stones under magnification and ask to see the certificate before money changes hands.
The 4Cs
Cut, colour, clarity and carat.
Cut
Cut controls sparkle more than any other C. A well-cut diamond returns light cleanly; a poorly cut stone can look dull even with good colour and clarity.
Colour
Colour grades run from D, the whitest, down the alphabet. Many buyers get better value by choosing a near-colourless grade that still faces up beautifully.
Clarity
Clarity measures natural inclusions or growth features. The practical question is whether the stone is eye-clean, not just what the grade says.
Carat
Carat is weight, not size alone. Shape and cut quality affect how large a diamond appears on the hand.
Certification
GIA vs IGI: what the certificate tells you.
A certificate is the independent grading report behind the diamond. It records the stone's measurements, 4Cs, proportions and identifying details.
For natural diamonds, GIA is widely recognised as the grading authority. For lab-grown diamonds, IGI is common and well understood in the trade. Both can be useful, but you should compare diamonds on the same basis: same type, similar grades, similar certificate details.
Ask David to walk you through the report. Important lines include measurements, table, depth, polish, symmetry, fluorescence and any comments. A good certificate should make the diamond easier to understand, not more confusing.
Natural or lab-grown
Choose based on what matters to you.
Natural diamonds
Natural diamonds are mined, finite and valued for rarity and origin. They suit buyers who want a traditional diamond with long-standing market recognition.
Lab-grown diamonds
Lab-grown diamonds are real diamonds grown above ground. They often give more size for the same budget and are usually certified by IGI.
If the diamond is for a proposal, continue from the buying guide to Diagem’s bespoke diamond engagement rings in South Africa, where the ring is designed around the centre stone.
Factory-direct pricing
Why the supply chain matters.
Retail diamond prices often include showroom rent, display stock, sales staff, broker margins and brand markup. Factory-direct buying removes much of that noise.
Diagem works from the diamond trade side, not as a shopping-centre jewellery chain. That means David can compare certificate-for-certificate and explain where the price difference comes from.
If you already have a quote, send it through with the certificate details. David can tell you whether the diamond is fairly priced and whether Diagem can beat it like-for-like.
Bring this to the appointment
- Your approximate budget range
- Preferred shape or ring style
- Any certificate or quote you already have
- Whether you prefer natural, lab-grown or want to compare both
Book a viewing
Speak to David before you buy.
Book a private appointment in Houghton Estate, Johannesburg. David will explain the certificate, compare options and help you choose without pressure.
Verified Google reviews
What Our Clients Say
Recent public Google reviews for Diagem Diamonds. These reviews do not claim to be about this specific page unless the reviewer says so.
“I had a fantastic experience buying an engagement ring for Ashton. I had zero experience with diamonds, but he guided me patiently, honestly, and never pushy. He helped me find exactly the right ring in a short time, and the price was very fair. Highly recommend!”
“I am absolutely blown away by the experience of dealing with David - he is so knowledgeable, professional, and really went out of his way to find me the perfect stone... and gosh, it is the most beautiful gem i have ever laid my eyes on!! Thank you David”
“These guys were a pleasure to deal with. Nothing too difficult for David - answered all my queries and arranged my VAT (GST) refund- would recommend”
Reviews sourced from Diagem Diamonds’ verified Google Business Profile. View Diagem reviews on Google Leave a Google review
Visiting South Africa to buy diamonds?
International visitors can plan a Johannesburg diamond viewing or Cape Town appointment by prior arrangement with David before or during their trip.
Read the tourist diamond buying guide