Terms of use

The encyclopedia is reference, not advice

The twenty-two chapters, the atlas, the tables and the A to Z index are a reference work. They describe how gemstones form, how they are mined, cut, treated, graded and traded, and they cite their sources so you can check them.

They are not valuation advice, investment advice, legal advice or tax advice, and nothing in them is an offer to buy or sell anything. A price, a grade or a figure in a chapter describes the trade at the time it was written. Do not rely on it to price a stone in front of you, and do not use it as a substitute for a report from a laboratory.

We take accuracy seriously and every chapter is sourced, but gemmology moves and errors survive proofreading. If you find one, write to us and we will fix it.

Listings in the register

Stones in the register belong to the people offering them, not to us. We inspect a stone and check it against its laboratory report before publishing it, but the description, the report and the asking price come from the owner and the laboratory.

A listing is an invitation to enquire. It is not an offer, it does not bind anyone, and a stone can be sold or withdrawn before the page is updated. On a register stone we act for the seller and are paid by the seller, which is stated on every listing.

The sourcing service

Sending a brief starts a conversation, nothing more. It does not create a contract and does not oblige either of us to anything.

Work begins only under a separate written engagement that sets out the scope, the fee and the terms for that particular search. Where that agreement and these terms disagree, that agreement governs.

Fees are as described on the service page: a retainer when the search plan is agreed, a success fee on completion, and costs passed through at cost with receipts. The figures that apply to you are the ones in your fee letter.

What you may do with the content

Read it, quote it, link to it, teach from it, print it for yourself. If you quote it, say where it came from.

The text, the diagrams, the maps and the photographs are ours and remain ours. Do not republish the encyclopedia wholesale, do not sell it, and do not feed it into a product that reproduces it. The underlying facts about gemstones belong to nobody; the way they are written and drawn here does not.

Sources cited in the chapters belong to the organisations that published them and are used as references, not reproduced.

Using the site

Do not attack the site, scrape it in a way that degrades it for other readers, try to break into any part of it, or use it to do anything unlawful.

We may change, move or remove anything here at any time. The site is provided as it is. We do not promise it will be available without interruption or free of error, and we are not liable for indirect or consequential loss arising from its use. Nothing here limits liability for death, personal injury, fraud or anything else that cannot lawfully be limited.

Links out

Chapters link to laboratories, trade bodies, regulators and published research. Those sites are not ours and we do not control what they say or do. A link is a citation, not an endorsement.

Law and forum

These terms are governed by Swiss law. The place of jurisdiction is Fribourg, Switzerland. If you are a consumer in the EEA or the UK, this does not take away the protection of the mandatory rules of the country you live in.

Changes

These terms were last revised on 19 September 2026. The version published here is the one that applies.