Buying a gemstone: what collectors and newcomers should consider

Whether as a jewellery stone, a collector's piece or an investment — buying a gemstone raises questions for many at first. This guide gives a compact overview of the most important criteria.

The four Cs — and more

With diamonds, the four Cs (carat, colour, clarity, cut) are an established standard. With coloured gemstones such as sapphire, tourmaline or tanzanite, similar criteria apply but with different weighting: colour usually comes first, followed by clarity, cut quality and carat weight.

Treated or untreated?

Many gemstones in the trade are heated, dyed or otherwise treated to improve colour and clarity. That is not inherently disreputable, but it should be communicated transparently — and it influences value considerably. Untreated stones are rarer and as a rule more valuable.

Trace the origin

Where a stone was found often says a great deal about its quality and rarity. Reputable sellers state the origin of every individual piece rather than writing merely 'sapphire' or 'tourmaline'.

Single pieces rather than mass-produced goods

Unlike industrially manufactured jewellery, every natural gemstone is unique. Anyone who wants a particular piece should not hesitate too long — once sold, an individual stone is no longer available.

Being able to trust the seller

The most important factor when buying a gemstone is in the end often not the stone itself but the person selling it: transparent information on origin and treatment, clear photographs of the actual piece and the possibility of getting in touch directly all create confidence — particularly with higher-priced purchases.

Conclusion

Keep colour, treatment, origin and the seller in view and you will make a well-founded buying decision — whether a newcomer or an experienced collector.