Key takeaway: A gold and diamond buyer values a piece like a diamond ring in two parts, each valued separately: the gold, on its weight and purity against the live gold price, and the stones, on carat, colour, clarity, cut and certification against the Rapaport Diamond Report and what trade dealers will pay. At The Gold Avenue in Sandton both are tested in one appointment, with Niton XRF analysers for the metal and the Sherlock Holmes-Yehuda laboratory system for the diamonds.
Most jewellery of real value is both gold and diamond. An engagement ring, a tennis bracelet, a pair of diamond studs, a pendant on a chain. Sell it to a gold-only buyer and the stones are treated as dead weight. Sell it to a diamond-only buyer and the metal is an afterthought.
This guide explains how a combined piece is valued properly, when to sell it whole and when to sell the parts, and what happens when you bring it to The Gold Avenue in Illovo, Sandton.
What gold and diamond buyers do differently
A gold buyer weighs metal. A diamond buyer grades stones. A gold and diamond buyer does both, in the same room, and then answers the question that actually decides your money: is this piece worth more as jewellery than as its parts?
The Gold Avenue buys gold jewellery and diamond jewellery as core business, and has a local and international network of buyers for the right pieces and polished diamonds, who often pay more than local dealers.
How a diamond ring is valued: the metal and the stones are valued separately
| Part of the piece | What is measured | How it is tested | What sets the price |
|---|---|---|---|
| The gold | Weight in grams, less stones and fittings, and purity (375, 585, 750, 916 or 999) | Accurate scale and Niton XRF analyser | Fine gold content against the live international gold price, less refinery costs and margin |
| The diamonds | Carat, colour, clarity, cut, certification | Sherlock Holmes-Yehuda laboratory system and professional diamond testers | The Rapaport Diamond Report, marketability and what trade dealers will pay |
| The piece as a whole | Brand, craftsmanship, condition, wearability | Purchasing Consultant’s assessment | Demand for the finished piece locally and through the international network |
The gold is the simpler part. Stones, clasps, springs and solder are deducted from the weight, the purity is read on the XRF analyser, and the gold is priced at the live rate. The diamonds take judgement, and that is where buyers differ most.
The four Cs and the Rapaport report
A diamond is priced on carat, colour, clarity and cut, together known as the four Cs, along with its certification and how marketable it is.
Those grades are read against the Rapaport Diamond Report, the price reference the diamond trade works from, and then adjusted for marketability and for what trade dealers will actually pay on the day. A buyer who quotes a diamond price without referring to the four Cs and a trade reference is guessing.
GIA-certified versus non-certified diamonds
A GIA certificate records the four Cs as graded by an independent laboratory, and a certified stone is straightforward to price because the grades are already established and trusted by trade buyers. Keep the certificate with the piece if you have it.
No certificate does not mean no value. The Gold Avenue buys non-certified diamonds too, subject to due diligence on origin. The stone is tested on the Sherlock Holmes-Yehuda laboratory system, then assessed on the four Cs by the Purchasing Consultant.
How the gold in a diamond piece is tested
The hallmark on the metal is a guide, not proof, so the piece goes on a Niton XRF analyser, which reads the purity of the metal without scratching or cutting it. The reading is on the screen in front of you.
Weight is taken with the stones in, then the stones and fittings are deducted. On a small ring with a large stone, the gold weight can be a good deal less than the scale weight, and we show you the deduction rather than burying it in the offer.
Should you sell the piece whole or separately?
This is the decision a gold and diamond buyer is there to help you make, and it depends on the piece.
Sell it whole when
- It carries a recognised brand or designer name, in good condition, ideally with its box and papers.
- The craftsmanship and design have resale appeal as a finished piece of jewellery.
- The stones are well matched to the setting, such as a tennis bracelet with graded stones of consistent quality.
Sell the parts when
- The setting is worn, damaged or dated and has no resale value as jewellery.
- The centre stone is the real value and the metal is simply a mount for it.
- The stones are small and the gold weight is where the value sits.
Either way you are paid one figure, and we explain which route produced it. If you want a written appraisal before deciding anything, our guide on how to get jewellery appraised explains the difference between an appraisal for insurance and a valuation for sale.
Tennis bracelets, earrings and necklaces
The same method applies across the jewellery box.
- Tennis bracelets carry many small stones. Consistency of colour and clarity across the line matters, and the gold weight in the links is often substantial.
- Diamond earrings are valued as a pair when the stones match, and a single earring is still bought on its stone and its gold.
- Necklaces and pendants are often a small diamond on a heavy chain, where the gold carries the value.
Bring everything together. Odd pieces, broken settings and single stones are all assessed, and a piece you assumed was worthless sometimes turns out to hold a good stone. For a broader look at who buys finished jewellery in Johannesburg, see our guide to jewellery buyers.
Frequently asked questions
Do gold and diamond buyers pay for the stones or only the gold?
A proper gold and diamond buyer pays for both, valued separately. Diamonds are graded on the four Cs against the Rapaport report; the gold is priced on its fine content against the live gold price. A gold-only buyer deducts the stones and pays nothing for them.
Is my diamond worth more with a GIA certificate?
A certificate makes the stone easier to price and easier to sell on, because trade buyers trust the independent grades. A non-certified diamond is still bought after testing and due diligence, and larger uncertified stones are assessed on their own merits.
Why is the offer so far below the insurance valuation?
An insurance valuation is a replacement-at-retail figure. It includes manufacturing, design, branding, retail mark-up and replacement cost. A buyer pays on the underlying value of the gold and the stones, which is what can be realised when the piece is sold on.
Do you buy loose diamonds as well as set ones?
Yes. Loose stones, GIA-certified or not, are tested and graded in the same way as set stones. High-grade polished diamonds also qualify for our Buyback Agreement, which lets you sell now and buy the stone back on an agreed date at a predetermined price.
What should I bring to sell a diamond ring?
The ring, any certificate, valuation or receipt you have, and your SA ID, passport or SA driver’s licence with proof of banking details. Do not have the ring cleaned or the stone removed first.
Sell your gold and diamonds at The Gold Avenue in Illovo, Sandton
The Gold Avenue was founded in April 2022 as a modern, secure alternative to the pawn-shop trade. We are a member of the Jewellery Council of South Africa and a registered second-hand goods dealer under the Second-Hand Goods Act, and hold a Google rating of 5.0 from around 400 Google reviews.
Your appointment takes place in a private consultation booth on the 8th floor of Illovo Point. A Purchasing Consultant tests the gold and the diamonds in front of you and explains both valuations. If you accept, you sign a one-page Sale Agreement and are paid by immediate EFT or cash, subject to ID and compliance. Valuations are free, with no obligation, and the visit typically takes 10 to 15 minutes.
Find us at Office 804, 8th floor, Illovo Point, 68 Melville Road, Illovo, Sandton, 2196. We are open Monday to Thursday 08:00 to 17:00 and Friday 08:00 to 16:00. Saturday is by pre-booked appointment only, and we are closed on Sundays and public holidays.
Call 010 109 0080, WhatsApp 076 393 5429, or book a free valuation at https://thegoldavenue.co.za/request-a-quote/.
Written by Trent Saldsman, Founder and Managing Director, The Gold Avenue.
Trent Saldsman is the Founder and Managing Director of The Gold Avenue, the gold, diamond, Krugerrand and luxury watch buyer he established at Illovo Point, Sandton in April 2022, and a Finalist in the Absa Eric Ellerine Entrepreneur Award 2024. He built The Gold Avenue as a secure, professional and transparent alternative to the traditional pawn-and-gold-buying trade, and works with an extensive local and international dealer network to pay sellers more competitively for their gold, diamonds and watches.