A bridal buyer asked us last month: a supplier offered the same 1 carat lab-grown solitaire at a $180 difference depending on whether it came with a GIA or an IGI report. Which one should the store stock? The answer depends on the ticket, the customer's expectation, and the margin you are defending, not on which lab sounds more famous.
What each lab does
The Gemological Institute of America (GIA) is the lab that defined the 4Cs and the diamond grading system, and its grading is treated as the reference standard in the trade. The International Gemological Institute (IGI) is the largest independent lab by volume and is widely accepted for both natural and lab-grown diamonds, particularly in the lab-grown retail segment. You can compare the lab descriptions directly at the GIA 4Cs page and the IGI site. The practical trade difference is turnaround and cost: GIA charges more and takes longer, and its grading on borderline clarity grades is more conservative. IGI charges less and turns faster, which is why most lab-grown volume moves on IGI reports.
When GIA is worth the premium
Demand GIA for natural diamonds above roughly 1 carat, for stones in the $5,000-plus retail band, and for any piece a customer will resell or insure. On a natural solitaire, the GIA report is the document that protects the resale value three owners from now. The pricing and turnaround side of that choice is in GIA versus IGI pricing and turnaround, and the full report structure in how to read a GIA report.
When IGI is enough
For lab-grown solitaires under 1.5 carats, and for natural stones under $2,500 retail, an IGI report is accepted at most retail counters and saves you $150 to $400 per stone in grading cost and waiting time. The tradeoff: some online diamond comparison engines weight GIA reports more heavily, so a GIA stone may sell faster on a price-comparison site. If your store sells by appointment and by relationship, that gap matters less. The lab-grown specifics are in what a lab-grown report actually measures, and the multi-lab comparison in GIA versus IGI versus GRA.
What to ask a supplier who cannot show a report
If a supplier quotes a GIA-grade or IGI-grade stone without the report number, ask for the report number before you place the order, and verify it on the lab website before you pay. A report number you cannot verify is the single most common red flag in diamond wholesale. Also ask whether the report matches the stone by laser inscription: the girdle should carry the report number micro-inscribed, and you should be able to read it under 10x magnification. The verification method is in how to spot a fake GIA report. Compare the certification market context in what diamond certification actually means at retail.
Is IGI a real diamond certificate?
Yes. IGI is an independent laboratory accepted worldwide for natural and lab-grown diamonds. It is not a fake certificate; it is a different lab with a different cost and turnaround.
Which lab grades more conservatively?
GIA, typically. A stone graded VS2 by IGI can sometimes grade SI1 under GIA. That gap is part of the price difference you are paying for.
Do I need a report for every diamond I sell?
For stones over 0.5 carat, yes. Under 0.5 carat, a grading memo or a matched melee lot card is usually sufficient, but disclose what you are offering.
Can I upgrade a stone from IGI to GIA?
Yes, you can resubmit. It costs roughly $80 to $150 per stone plus turnaround time, and the grade may come back lower, so price that risk before you promise the customer.
How the report follows the stone through a setting job
When you send a loose stone to be set, the report does not go to the bench; it stays with you as the store owner. The bench receives a work order that references the report number and the stone's carat and dimensions, and the finished setting is checked against those dimensions on return. Keep the report in the customer's file, and hand a copy over when the customer picks up the finished piece. If the customer ever resizes, resets, or insures the ring, that report number is the single reference point everyone uses. A store that files the report with the work order also avoids the most common dispute: a customer who comes back a year later convinced the stone was swapped. The laser inscription on the girdle, matched to the report number, settles it in one look. Build that step into your bench checklist so it happens on every report-backed order, not just the expensive ones.
Need a bridal program with the right report for the ticket? HOLYCOME supplies natural and lab-grown solitaires with GIA or IGI reports as specified, report numbers verified before shipping, and low first-order MOQ. Read our first-order checklist or request a report-backed quote.
Frequently Asked Questions
How do I verify a factory before placing a bulk order?
Request a production video, business license, export records and a paid sample run. A factory that accepts a 50-piece test order is usually a real manufacturer.
What payment terms do you offer?
30% T/T deposit with the balance against the bill of lading. This protects both sides on first orders and can move to net terms after a track record.
What is your normal reject rate?
3–5% under 10x loupe inspection for cast and set pieces. Defective units are replaced free in the next shipment.
Where is the factory located?
Wuzhou, Guangxi, China—the core lab-grown and moissanite manufacturing cluster. Shipments go via Guangzhou or Shenzhen ports.
