Install the Gem Encyclopedia app
The Maxime Voillot Gems encyclopedia: 281 stones and minerals, more than 1,100 high-definition photos, every gemmological property (hardness, density, colours, transparency, deposits by country...), in French and in English. Once installed, it works fully offline — perfect when travelling, at a trade show or in the field.
1. Buy your access code
Add the app to your cart and complete your order. You will receive by e-mail a personal access code (format GEM-XXXX-XXXX), valid for your device.
ℹ️ Can't find the e-mail? Check your junk/spam folder, as well as the “Promotions” or “Updates” tabs if you use Gmail.
2. Open the app
On the phone where you want to install it, open this link, preferably on Wi-Fi (the first load downloads the entire encyclopedia, photos included, ≈ 35 MB):
⚠️ On iPhone/iPad, open it in Safari. On Android, in Chrome.
3. Enter your code
Type the code received by e-mail, then tap “Unlock”.
4. Add it to your home screen
iPhone / iPad (Safari): tap the Share button (the square with an upward arrow) then “Add to Home Screen” and “Add”.
Android (Chrome): tap the ⋮ menu at the top right then “Add to Home screen” (or “Install app”).
The emerald icon 💎 appears on your home screen: the app opens full screen, like any other app.
ℹ️ On first launch from the icon, the app may ask for your code again: this is normal (the installed app is independent from the browser). Simply enter the same code a second time — your code covers this double activation.
5. Use it anywhere, even with no network
After the first opening, everything is stored on your device: entries, high-definition photos, filters. On a plane, abroad or at the bottom of a mine, the encyclopedia remains available.
Frequently asked questions
I did not receive my activation code by e-mail. First check your junk/spam folder — the most frequent cause. On Gmail, also look in the “Promotions” and “Updates” tabs. If you still cannot find it, write to us with your order number and we will resend the code.
The app asks for the code again after installation. This is normal: enter the same code a second time. Your code covers activation in the browser and in the installed app.
Some photos do not appear offline. Reopen the app for a few minutes on Wi-Fi: it completes its download automatically.
My code does not work. Each code is personal and limited to one device. If it has already been used elsewhere, contact us with your order number.
I am changing phones. Write to us with your order number and we will provide a new code.
The app will not install. Make sure you are using Safari (iPhone) or Chrome (Android) — the in-app browsers of Facebook/Instagram do not allow installation.