Gemstone auction checklist: 12 checks before you bid online

Before bidding on a gemstone at an online auction, check the paperwork first, then the stone, then the rules. Make sure the lot has a full report from an independent laboratory that matches the stone and can be verified online, read the treatment and origin wording exactly as the lab wrote it, and work out the total cost, closing rules and complaint deadlines before you place a bid you cannot withdraw.

The gemstone auction checklist

These twelve checks apply to any online gemstone auction. Where a rule is specific to Catawiki, we say so and cite its own help pages.

1. Is it a full report or only an ID card?

A full report sets out the identification, the measurements and the treatment findings. Catawiki's gemstone submission guidelines require a full original certificate from an approved gemmological institute and state that ID cards and preliminary reports are not accepted; nor are uncertified stones. On any other platform, treat a card or a seller's own description as a starting point, not as evidence.

2. Which laboratory issued it, and is it independent?

A report is most useful when it comes from a laboratory with no stake in the sale, not from the seller or an affiliated company. Catawiki works from its own list of approved institutes. The Laboratory Manual Harmonisation Committee (LMHC), whose members are CGL, CISGEM, DSEF, GIA, GIT, Gübelin and SSEF, sets common report wording; labs outside it, such as GRS, Lotus Gemology, Bellerophon Gemlab and GUILD, use their own.

3. Does the report match the stone, and how old is it?

GIA's coloured stone reports record weight, measurements, shape and cutting style. Compare each of these with the lot description: a different weight or outline is a reason to stop. Then look at the date. A report describes the stone on the day it was tested. In June 2026, as Rapaport reported, SSEF warned that some emeralds were being cleaned and refilled after testing and offered with earlier reports that no longer reflected their condition.

4. Can you verify the report number online?

GIA, for example, offers Report Check, which it describes as a secure online database for confirming that a product description matches the grading results. Enter the number yourself on the laboratory's own website rather than following a link in the listing. Our guide on how to verify a gemstone lab report walks through the main laboratories.

5. What exactly does the treatment line say?

Under the LMHC's current wording for corundum, "no indications of heating" (NH) and "indications of heating" (H) are different statements, and where heating has left residues in fissures they are graded as minor, moderate or significant. Older reports may show earlier codes (NTE, TE1 to TE5), and labs such as GRS and Lotus use their own. Catawiki excludes non-traditional treatments such as lead glass, fillers, dyes and coatings. For what the distinction means for price, see unheated versus heated ruby and sapphire.

6. Is the origin on the report, or only in the title?

Catawiki's guidelines allow a country of origin to be stated only if the certificate specifies it; otherwise the description must carry an origin disclaimer. GIA gives origin only where it can be determined and applies to the gem type. If "Burma" or "Kashmir" appears in the title but not on the report, it is not established.

7. Are colour names the lab's or the seller's?

Terms such as "pigeon blood" and "royal blue" carry a premium, so check whether the report itself uses them. A trade term in a lot title is a description, not a finding. Our guides to what pigeon blood means at each laboratory and royal blue sapphire by lab explain how laboratories apply them.

8. Do the photos show the stone in daylight?

Catawiki recommends five sharp images showing the top, bottom and sides of a stone, plus a readable image of the full certificate, and asks sellers to name the light source when photos are not taken in daylight. Colour shifts between lighting conditions, so where possible ask for a short video in daylight and compare it with the colour described on the report.

9. Do you understand the reserve and closing rules?

A reserve is a hidden minimum price, set by the seller with an expert, that Catawiki does not disclose before the auction ends; it is available only for objects expected to fetch at least €200, and if bidding stays below it the object is not sold. A maximum bid lets the system raise your bid in the smallest steps up to your limit and never beyond it, and the minimum next bid depends on the current one. A bid placed in the last 60 seconds adds 90 seconds to the clock, or 10 seconds for a bid in the last 15 seconds of a Live auction. Every bid is binding.

10. What will it cost in total, and where does it ship from?

On Catawiki the winning bid carries a buyer protection fee of 9% plus €3, the seller sets the shipping charge, and the object page shows where the stone ships from. That location decides whether import VAT, duty or carrier fees follow. Our breakdown of what an online gemstone auction really costs works through examples for a Swiss buyer.

11. Do you know the protection rules and deadlines?

Catawiki holds the payment and releases it to the seller up to 3 days after delivery. If the stone is not as described, its help centre asks buyers to report within 3 days of delivery, with photos of the whole object, at least two close-ups, the packaging and the shipping label, so that the seller's payment can be paused. Its Buyer Terms say payment is due within 3 days of the auction ending, that return shipping is usually at the buyer's cost, and that buyers in the EU or UK purchasing from a professional seller may have a 14-day right of withdrawal, which does not apply to private sellers.

12. Should you get a second opinion?

For high values, yes. Catawiki's guidelines say a second certificate may be required for rare or high-value stones, and GIA's advice on buying diamonds online recommends an independent appraiser check the item against its paperwork on arrival. Because the reporting window is short, arrange the appointment before you bid, not after the parcel lands.

Bid on the report, not the photograph; then confirm the stone matches both.

How does this compare with buying at a fixed price?

At auction these checks must be done against a closing clock, with the total fixed only when the lot ends; a fixed-price dealer lets you check at your own pace and see the full cost upfront, though without the chance of a bargain. Our certification and treatments page sets out how we document each stone, and our gemstone collection lists every stone at a fixed price with its laboratory, report number and treatment status. You can request a quotation or ask a question on WhatsApp from any product page.

This article summarises published platform rules and laboratory practice as of October 2026; rules and fees change, so check the current terms before bidding. It is general information, not investment, tax or legal advice.

Frequently asked questions

Does Catawiki accept gemstones without a certificate?

No. Catawiki's gemstone submission guidelines require a full original certificate from an approved institute and exclude uncertified stones, ID cards and preliminary reports.

Does a last-minute bid extend a Catawiki auction?

Yes. According to Catawiki, a bid in the final 60 seconds adds 90 seconds to the end time; in a Live auction, a bid in the last 15 seconds adds 10 seconds.

Can I see the reserve price before bidding?

No. Catawiki keeps the reserve hidden until the auction ends, and if the highest bid is below it, no sale takes place.

How long do I have to report a problem with a stone bought on Catawiki?

Catawiki asks buyers to contact it within 3 days of delivery. After that, it assumes the order went smoothly and the seller is paid.

What does "no indications of heating" mean on a report?

In the LMHC's standard wording for ruby and sapphire (code NH), it means the laboratory found no indications that the stone was heated. "Indications of heating" (H) means it found such evidence.