What's the difference between a GIA and an IGI diamond certificate?

Both are recognised independent grading labs, but GIA is generally regarded as the stricter grader, particularly for mined diamonds, and doesn't disclose growth method or treatment history on lab-grown reports. IGI has graded lab-grown diamonds since 2005 and typically states the growth process (CVD or HPHT) and any post-growth treatment, but its grading is often considered a shade more generous than GIA's on the same stone.

Can I buy a loose diamond online and bring it to a workshop to be set?

Most workshops will accept this, though policies vary — some charge a setting fee that reflects the extra inspection, measurement and liability involved, and a few decline outside stones for certain designs entirely. Confirm the policy and any additional cost before you buy the stone, not after, since it affects the total budget.

Should I buy a certified stone or an uncertified one to save money?

For any diamond of meaningful value, an independent certificate from a recognised lab is worth insisting on, because it's the only objective record of the stone's actual quality and it protects you if a dispute arises later. Uncertified stones can be cheaper but leave you relying entirely on the seller's word, which is a real risk for anything beyond a small accent stone.

Are lab-grown diamonds treated differently when it comes to sourcing and certification?

They're sourced through largely the same trade channels as mined diamonds — dealers, wholesalers and increasingly dedicated lab-grown suppliers — and certified by the same major labs, GIA and IGI among them. The main practical differences are price, which is substantially lower than mined stones of equivalent grade, and that reputable certificates for lab-grown stones always disclose that the diamond was grown, not mined.

Can I choose my own diamond for a bespoke ring — or supply one?

Yes, in most bespoke commissions you have real choice over the stone, whether that means reviewing options a jeweller sources for you or bringing your own. How much choice, and how straightforward it is, depends on the route you take — sourcing through the workshop is usually the smoother path, while supplying your own stone comes with genuine trade-offs worth understanding before you commit to it.

How jewellers actually source stones

Most workshops don't hold large stocks of loose diamonds and gemstones on site. Instead, they source stones on request through a small number of trade channels once they know what a client is looking for — shape, size, quality range and budget.

Diamond dealers and wholesalers are the most common route. These are trade suppliers who deal in loose stones rather than finished jewellery, and a workshop with established trade relationships can usually call on several dealers to find stones matching a specific brief, often within a working week or two for standard shapes and sizes. Diamond bourses — trading exchanges concentrated in centres like Antwerp, London's Hatton Garden and historically Mumbai and Surat for cut and polished stones — are another source, generally used by dealers themselves rather than jewellers buying directly, though some workshops have direct bourse access through longstanding trade relationships.

For unusual requests — a specific fancy shape, an antique cut, a coloured stone in a particular tone — sourcing can take longer and involve viewing several options from different suppliers before settling on the right one. This is normal, and worth building into your timeline expectations if your brief calls for anything outside the common round-brilliant, standard-clarity range.

Lab-grown diamonds are sourced through a related but increasingly distinct set of channels. Wholesale lab-grown suppliers sell directly to the trade — independent jewellers, designers and manufacturers — often at prices well below equivalent retail lab-grown pricing, and the wholesale price of lab-grown diamonds has fallen substantially in recent years as production has scaled up. Most workshops that offer lab-grown options can source a wide range of sizes and qualities relatively quickly, since supply is generally more plentiful than for comparable mined stones.

Viewing a stone before you commit

For any stone of meaningful value, ask to see it — or clear, high-resolution images and video of it — before it's set. A certificate tells you the graded specifications, but viewing the actual stone, ideally under proper lighting and magnification, is the only way to judge how it looks in person, which sometimes differs from what the numbers on paper suggest. Two diamonds with identical certificate grades can look subtly different to the eye, and this matters more for larger stones or for coloured gemstones, where grading standards are less standardised than for diamonds.

If you're not local to the workshop, ask whether they can arrange a video call viewing or send detailed photography before the stone is purchased on your behalf. Reputable workshops are generally used to this request and can accommodate it without difficulty; reluctance to let you see a stone before it's bought is worth treating as a caution sign.

Certificates: GIA and IGI

For diamonds above a certain size — typically anything from around a third of a carat upward, though practice varies — an independent grading certificate is standard practice and worth insisting on. The two labs you'll most commonly encounter are GIA (the Gemological Institute of America) and IGI (the International Gemological Institute).

GIA is generally regarded as the stricter and most consistent grader in the trade, particularly for mined diamonds, and its certificates carry the most weight among specialists and at resale. IGI has built a strong reputation specifically in lab-grown diamond grading — it began grading lab-grown stones considerably earlier than GIA did — and its lab-grown certificates typically disclose the growth method (CVD or HPHT) and any post-growth treatment, detail that GIA's reports don't include. In practice, grading between the two labs can differ slightly on the same stone, with IGI sometimes considered a touch more generous than GIA on borderline grades; this is a known pattern in the trade rather than a reason to distrust either lab outright, but it's worth knowing when comparing stones certified by different labs.

Whichever lab is used, check that the certificate number, measurements and any inscription on the stone's girdle (if present) match what you've been shown, and keep the certificate safe afterward — it matters for insurance as well as for any future resale or valuation.

Can you supply your own stone?

Most workshops will accept a stone you've bought elsewhere and set it into a bespoke design, but this needs an honest look at the trade-offs rather than an assumption that it works exactly like sourcing through the workshop.

Setting risk and liability. When a jeweller sets a stone they didn't sell you, they're taking on risk for a stone whose full history — how it was cut, whether it has hidden inclusions close to the surface, whether it's been treated in ways that affect how it responds to heat or pressure during setting — they don't have complete visibility into. Because of this, many workshops ask clients to sign a liability waiver before setting an outside stone, acknowledging that the jeweller isn't responsible if a pre-existing vulnerability in the stone causes a problem during the setting process itself.

No warranty on the stone. A jeweller who sells you a stone as part of a commission typically stands behind it in the way any retailer does. A stone you've sourced yourself doesn't carry that relationship — if it turns out to be misrepresented, damaged, or not what the certificate claimed, the workshop setting it has no obligation to make it right, because they didn't sell it to you. Any dispute sits between you and wherever you originally bought the stone.

Some workshops charge more, or decline outside stones altogether. It's common for workshops to apply a setting fee specifically for outside stones, reflecting the extra time spent inspecting and measuring a stone they didn't source, plus the liability they're taking on. A smaller number decline to set outside stones for certain designs — particularly intricate pavé or micro-setting work — where the risk of damage during setting is higher and the workshop would rather not take on a stone they can't warranty. It's worth asking directly about a workshop's policy before you buy a loose stone elsewhere, rather than assuming it will be accepted on the same terms as a stone sourced through them.

None of this means supplying your own stone is a bad idea — it's a completely normal and common choice, particularly for inherited stones, stones bought at a favourable price independently, or stones with sentimental history. It simply means going in with clear expectations about liability, warranty and cost, rather than assuming it works identically to letting the workshop source the stone for you.

The bottom line

You generally have real choice over your stone in a bespoke commission, whether that means reviewing stones a jeweller sources through their trade network or supplying one yourself. Sourcing through the workshop is usually the more straightforward path, with the jeweller taking on responsibility for what they sell you. Supplying your own stone is entirely workable but shifts real risk and cost back onto you — no warranty on the stone itself, possible setting fees, and occasionally a workshop that would rather not take it on at all. Either way, insist on independent certification for anything of meaningful value and view the actual stone, not just its paperwork, before it's set.