Factory-Direct GIA Certified Diamonds. Since 1999.
No middlemen. No retail markup. Every GIA certified diamond sourced and priced directly through the diamond trade — by a real person who's been doing this for 25 years.
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What Are GIA Certified Diamonds?
The Gemological Institute of America (GIA) is the world's most respected diamond grading laboratory. When a diamond is "GIA certified", it means an independent team of expert gemologists has examined the stone and issued an official report verifying its quality — with no connection to the seller.
GIA created the 4Cs system that the entire diamond industry uses today. Their grading is recognised and trusted by dealers, insurers, and buyers in every major diamond market worldwide. A GIA report is the closest thing to a passport for a diamond — it tells the full story of exactly what you're buying.
What GIA Grades Every Diamond On
Cut — The Most Important
GIA grades cut from Excellent to Poor. Cut determines how brilliantly the diamond reflects light. An Excellent cut makes every other grade look its best. Always prioritise cut above all else.
Colour — D to Z Scale
GIA grades colour from D (completely colourless) to Z (noticeably yellow). Most buyers find stones in the G–I range eye-clean and excellent value — the colour difference from D is invisible to the naked eye.
Clarity — Flawless to Included
GIA grades clarity from Flawless (no inclusions under 10× magnification) to Included. VS2 or SI1 grades are often eye-clean and significantly more affordable than the top grades, with no visible difference.
Carat — Weight, Not Size
Carat is the diamond's weight. A well-cut stone of slightly lower carat weight can appear larger than a heavier, poorly cut one. David guides every client to maximise visible size within their budget.
GIA vs IGI — Which Certificate Should You Choose?
Both are respected laboratories. Here's the honest difference so you can make the right call for your budget and priorities.
GIA
Gold standard. Founded in 1931. The grading benchmark every other lab is measured against. Known for the strictest, most consistent standards in the industry. GIA reports command slightly higher premiums because the market trusts them completely. Best choice for natural diamonds, high-value purchases, and investment pieces.
IGI
Widely accepted & reputable. The International Gemological Institute is the world's largest independent gem lab, with extensive presence in South Africa. IGI is particularly popular for lab-grown diamonds and is accepted by all major insurers and retailers. Excellent choice for budget-conscious buyers who want independent certification.
David's Honest Advice
For natural diamonds above 0.50ct, GIA certification gives the strongest resale confidence and is worth the small premium. For lab-grown diamonds, IGI is excellent value. Whatever certificate you're looking at — GIA, IGI, or anything else — call David and he'll tell you if the specific stone is a good buy.
Why Buy GIA Certified from Diagem?
25 years in the South African diamond trade. DDC SA and WFDB member. Factory-direct pricing with no middlemen — and a real person who answers the phone.
A Real Person, Not a Website
Call David. He picks up. No chatbots, no call centres, no automated responses. Every GIA diamond enquiry is handled personally by someone who has been in the trade for over 25 years.
Certificate in Hand Before You Pay
You receive the original GIA certificate. You verify the grading on gia.edu yourself. Not a word of what we say about a diamond matters until you've checked it against GIA's own database.
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Factory-Direct Pricing
We sit at the top of the supply chain — no middlemen, no wholesale markup, no retail showroom costs. The same GIA certified diamond costs significantly less from Diagem than behind a retail counter.
Beat Any Quote, Guaranteed
Send us a competitor's quote with the GIA report number. We'll beat it on any like-for-like certified stone. Factory-direct means you always pay less.
→📞 082 551 2103 — Call or WhatsApp David directly
Think You Found a Better Price? Send It to Us.
As diamond polishers and dealers, we sit at the very top of the supply chain. In most cases we can beat — not just match — any like-for-like GIA certified diamond quote you receive elsewhere.
Send us the quote with the GIA report number and we'll get back to you fast with a better price.
Send Your Quote →GIA Certified Diamond Collection
Every category below can be supplied with GIA certification. Tell us what you're looking for and David will source the exact stone.
GIA Certified Natural Diamonds
Loose certified natural diamonds in every shape and carat. Sourced and priced factory-direct.
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GIA Diamond Engagement Rings
Commission a bespoke ring built around a GIA certified centre stone of your choice.
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GIA Certified Diamond Earrings
Matched pairs of GIA certified diamonds, set into classic or bespoke earring designs.
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All Diamond Shapes Available
Round brilliant, oval, cushion, princess, emerald, radiant, pear, marquise, asscher and heart — all GIA certified.
→Industry Credentials
Membership of these bodies requires proven ethical standing and years of established trading. They're how you know you're buying from a legitimate dealer, not a reseller.
Diamond Dealers Club of South Africa
Full member of the DDCSA — South Africa's leading body regulating diamond dealers. Only established, ethical dealers are admitted. Membership is not bought; it's earned.
World Federation of Diamond Bourses
Member of the WFDB — the global authority representing diamond bourses in over 30 countries. Diagem is recognised at the highest level of the international diamond trade.
GIA & IGI Certified Stones
Every diamond we supply is independently graded by GIA or IGI. The certificate is yours to verify. We deal in certified diamonds only — no uncertified stones, ever.
First-Time Buyer? Here's the Call David Promise.
You don't need to know anything about diamonds before you call. That's what David is for.
Call or WhatsApp David
082 551 2103. A real person answers. Tell him your budget and what the diamond is for — he takes it from there.
Plain-Language Education
David explains GIA certification, the 4Cs, and what actually matters for your specific purchase. No jargon. No assumptions about what you already know.
Shortlisted GIA Options
David presents shortlisted GIA certified stones matched to your budget and preferences, with full certificate details for each.
View in Person (Optional)
By appointment at our Johannesburg offices. Inspect every stone under magnification with the GIA certificate in your hand.
Delivered Insured
Fully insured courier delivery anywhere in South Africa. Tracked, secured, and insured for full replacement value.
"No obligation. No pressure. Just honest advice from a 25-year industry veteran."
With over 25 years in the South African diamond trade, we leave no stone unturned to find exactly the GIA certified diamond you're looking for. Every enquiry is handled personally by David — no chatbots, no automated responses. Real expertise. Real service.
📞 082 551 2103Let's talk →
GIA Diamond FAQ
What is a GIA certified diamond?
Is GIA better than IGI?
Can Diagem source a specific GIA certified diamond for me?
Will I pay less for a GIA diamond at Diagem than at a retail jeweller?
How do I verify a GIA certificate is genuine?
Do GIA certified diamonds hold their value better?
Call David. He'll sort it out.
Whether you're buying your first diamond or your tenth — David handles every GIA diamond enquiry personally. No pressure, no obligation. Just honest advice from someone who has spent 25 years in the trade.