Support

Email support@gemmo.app and a person will read it.

What does 750 mean? And 585, 925, PT950?

They are purity marks. A bare number is a millesimal mark — parts per thousand, the European convention. So 750 means 750 parts gold in every 1000, or 75% pure. A number followed by ct in Britain, or K in America, is the same fact counted in carats: 18ct, 18K and 750 are all the same gold. These are the marks Gemmo decodes:

• 375 — 9 carat gold, 37.5% pure.
• 417 — 10 carat gold, 41.7% pure.
• 585 — 14 carat gold, 58.5% pure.
• 750 — 18 carat gold, 75% pure.
• 916 — 22 carat gold, 91.6% pure.
• 925 — sterling silver, 92.5% pure. The standard alloy for jewellery and flatware.
• 999 — fine silver. It also marks 24 carat gold, so the colour settles which.
• PT950, PLAT, 950 — platinum, 95% pure. Noticeably heavier than gold.

A mark Gemmo doesn't recognise is usually a maker's mark rather than a purity mark, or a purity mark worn too far to read. It will say so instead of guessing.

How do I photograph a hallmark so it can be read?

The stamp is about a millimetre across, struck rather than printed, and the same colour as the metal around it — which is why ordinary text scanning struggles with it. Four things help more than anything else:

• Photograph the whole piece first. Gemmo asks for the hallmark separately if it needs it.
• For a hallmark shot, leave some metal around the stamp — about a third of the frame. Filling the frame with the stamp makes it harder to read, not easier.
• Turn the torch on. Engraving only shows up when the light casts a shadow in it.
• Rest your hands on something solid and let the camera focus.

Gemmo has a macro mode for this shot: move the phone close to the stamp and it switches to the ultra-wide lens, the same way the system camera does. If it still can't read the mark, you can type the characters in yourself — a stamp you read with your own eyes is decoded by exactly the same logic as one the camera reads.

What is melt value?

Melt value is what the precious metal in a piece is worth as raw metal: weight × purity × today's spot price. It is the one number about a piece of jewellery that can be calculated rather than judged, which is why Gemmo leads with it. A 10 g 18ct gold ring is 75% gold, so 7.5 g of gold priced at the current market rate.

It is a floor, not a valuation. It ignores gemstones, brand, age and craftsmanship, any of which can be worth many times the metal.

Why is my value a range and not one number?

Because the weight is the uncertain part. Purity comes from the hallmark and the spot price comes from the market, but a photograph can only estimate how much the piece weighs — so the range is wide, about ±25%. Put the piece on a kitchen scale and enter the exact weight, and the range tightens to roughly ±5%, which is just spot and scale noise.

If a result still looks wrong, check the purity Gemmo read against the stamp on the piece. A misread mark moves the value far more than a misjudged weight does.

Why would a jeweller offer me less than this?

Because spot is the ceiling, not the offer. A buyer has to refine the metal, carry the risk on the price between now and then, and make a margin — so a real offer sits under melt value, often well under. Gemmo shows the melt figure so you walk in knowing what the metal is worth, not so you can expect a cheque for it.

Gemmo also shows a rough resale range above melt. That one is an estimate, not a calculation — treat it as a ballpark and confirm anything that matters with a jeweller.

Where do saved pieces go?

Tap Save on a result and the piece lands in the Jewelry Box tab with its photo, purity and value. Nothing is saved automatically — a result you don't save is not counted in your collection total. You can filter the box by metal, or show only the pieces whose weight you measured exactly.

From there you can export the collection as a dated PDF for an insurer or an inventory: each piece with its metal, purity and value range, and the estimated total at the end. You can also share a single piece the same way.

How do I cancel my subscription or get a refund?

Manage or cancel in Settings → Manage subscription, or in your Apple Account. Refunds are handled by Apple, not by us — request one at reportaproblem.apple.com. If you were charged and the app still shows you as free, tap Restore purchases first, then email us.

The three free scans only count when a scan actually produces a result. If a photo comes back unreadable, it hasn't cost you one.

How do I report a bug?

Tell us what you did, what happened, and what you expected. Your iPhone model and iOS version help. If a scan produced a wrong result, the photo helps most of all — but only send it if you are comfortable doing so.