Privacy Policy
Last updated 2026-10-03
The short version. The photograph you take is sent through Gemmo's own server, which does not keep it, to Google's Gemini API to be analysed. Your Jewelry Box stays on your iPhone. The app also sends anonymous usage events to Mixpanel to help improve it, never your photographs or results. There is no advertising, no tracking across apps or websites, and no account required.
Who is responsible
Gemmo is published by an independent developer acting as the data controller in a personal capacity, based in Germany. Contact: support@gemmo.app.
Photographs — the part that leaves your device
When you scan a piece, the photograph is uploaded to Gemmo's own server at api.gemmo.app, which passes it to the Google Gemini API to identify the item and read any hallmark in the image, and sends the result back to the app. This is the only way the app works: the analysis does not run on your iPhone.
Send only photographs you are comfortable sharing with a third party. A photograph can contain more than you intend — a reflection, a document behind the piece, a face. Gemmo does not inspect images for anything beyond the jewellery, but it cannot control what is in the frame.
Gemmo's server does not store photographs or results: it holds a photo only for the seconds the analysis takes. With each scan the app sends its random install identifier (below), and the server keeps that day's scan count under a one-way hash of it, to apply a fair daily limit; to give Gemmo Premium its higher limit it asks RevenueCat whether that install has an active subscription. The counts delete themselves within three days. The server's request logs carry the same hash, never the photograph, the result or your IP address. Cloudflare, which runs the server, handles your IP address to deliver each request and to block abuse.
Google's handling of API data is governed by its own terms; see the link in the table below. The copy of the photo attached to a saved item stays in the app's own storage on your device.
What stays on your device
- Your Jewelry Box — every saved piece, its photo, purity, and estimated value — is written to the app's private storage on the iPhone. It is not uploaded anywhere, and there is no cloud sync.
- Your preferences (currency, weight unit) and your free-scan count.
- A random install identifier, generated on the device, used to attach a subscription to this installation, with each scan to apply the daily scan limit, and to group the anonymous usage events described below. It is not an Apple ID, not an email, and is not linked to you.
Deleting the app deletes all of it. On our side there is only the day's scan count under a hashed identifier, which deletes itself within three days, and the anonymous usage events described below.
Usage analytics
Gemmo uses Mixpanel as its product-analytics service. Mixpanel receives anonymous usage events: which features you use (for example "a scan started" or "a piece was saved"), the general shape of a scan result (the metal, the purity band, whether a hallmark was read and the authenticity verdict, never the photograph, the description, the hallmark text or any value), basic app and subscription context (app version, whether Premium is active), and an approximate region derived from your IP address. All of it is tied to the random install identifier described above. No name, email, phone number or advertising identifier is sent, Mixpanel's automatic data collection is switched off, and there is no session replay: your screen is never recorded.
Mixpanel's privacy policy applies, and it stores this data on US infrastructure; for users in the EU or UK, that transfer relies on the Standard Contractual Clauses Mixpanel provides to its customers. To have the events tied to your install deleted, email support@gemmo.app.
Sign in with Apple
Optional, and currently local-only: signing in stores the identifier Apple returns on your device so the app can show your name. It does not create an account with us and does not upload anything. If Apple gave you a private relay email address, we never see mail sent to it because we run no mail server to receive it.
Who processes data
| Processor | What it does |
|---|---|
| Google (Gemini API) | Analyses the photograph you take, passed on by Gemmo's server, to identify the piece and read its hallmark |
| Cloudflare | Runs Gemmo's server (api.gemmo.app), which passes photographs to Gemini without storing them, relays spot prices, and keeps hashed daily scan counts for three days |
| GoldAPI | Live precious-metal spot prices, fetched by Gemmo's server and shared by all users. Receives no personal data, not even your IP address — only which metal and currency to quote |
| RevenueCat | Subscription and entitlement management. Gemmo's server also asks it whether an install has Gemmo Premium, to set that install's daily scan limit |
| Mixpanel | Anonymous product analytics: which features are used and the general shape of a scan result (metal, purity band, verdict), tied to the random install identifier. Never photographs, descriptions, hallmark text or values |
| Apple | App Store purchases and Sign in with Apple |
What we do not do
- No crash-reporting SDK, no session replay, and no advertising SDK.
- No advertising, no ad identifiers, and no App Tracking Transparency prompt: nothing is used to track you across other companies' apps or websites.
- No selling or sharing of personal information, as those terms are used in US state privacy laws.
- No profiling and no automated decision-making with legal effect. A melt-value estimate is information, not a decision about you.
Legal basis, if you are in the EEA or UK
Processing a photograph you chose to scan is necessary to perform the service you asked for (GDPR Art. 6(1)(b)). Keeping your subscription status and the day's scan count is the same. Anonymous usage analytics rely on our legitimate interest in operating and improving the app (Art. 6(1)(f)); you can object by writing to us. There is no processing for marketing.
Your rights
You can access, correct, export or erase your data by opening the app — almost all of it is on your device, and deleting the app erases it. To have the anonymous usage events tied to your install deleted from Mixpanel, email us. For anything a processor above holds, use the contact route in its own policy. You may also complain to your local supervisory authority. Write to support@gemmo.app and we will help where we can.
Children
Gemmo is not directed at children under 13 and we do not knowingly collect their data.
Changes
Material changes will be reflected here with a new date at the top. If the app ever starts collecting a new kind of data, this page changes before that ships.