Buying and owning high jewellery and important gemstones

At a glance

• Who it is for: buyers of high jewellery, signed period pieces and important loose or mounted gemstones.
• The three things that matter most: reports from recognised gemmological laboratories (grading, origin, treatment); ethical and legal sourcing; and specie insurance with up-to-date valuations.

Understanding the market

• Segments: important white and coloured diamonds; coloured gemstones (ruby, sapphire, emerald and rarer stones); natural pearls; signed jewels from major houses; period jewellery (e.g. Georgian, Victorian, Art Deco); contemporary high jewellery.
• Value drivers: for diamonds, the "4Cs" (carat, colour, clarity, cut) plus fluorescence; for coloured stones, colour, origin and absence of treatment; maker's signature; period; provenance (notable owners).
• Laboratory-grown diamonds are chemically diamond but sit in a separate, much lower-priced market; disclosure is essential.

Ways to own

• Jewellers and high-jewellery maisons.
• Auction houses (major jewellery sales are held in Geneva, New York and Hong Kong).
• Dealers and private sales; bespoke commissions.

Where and how to buy

• Ask for reports from internationally recognised laboratories; for coloured stones, origin and treatment reports.
• Check that the report matches the stone (inscriptions, measurements, plotting).
• At auction, understand buyer's premium and any import VAT on lots under temporary admission.

Due diligence and authenticity

• Independent re-verification of laboratory reports for significant stones.
• Treatment disclosure: heat, fracture-filling, oiling, irradiation, coating — each affects value.
• Natural versus cultured pearls; natural versus laboratory-grown diamonds.
• Sourcing: Kimberley Process certification for rough diamonds, sanctions on certain origins, and responsible-sourcing policies.
• Hallmarks and maker's marks for signed and period pieces.

Costs of acquisition and ownership

• One-off: retail margin or buyer's premium; import VAT/duty; laboratory reports; resizing or remounting.
• Recurring: specie insurance; valuations (commonly every few years); cleaning and checks of settings; safe or vault storage.

Structure, tax and regulation — topics to raise with your advisers

• Treatment of gifts and inheritance of jewellery within your family.
• Customs declarations when travelling with jewellery.
• Disposals and any personal-chattel rules where you live.

Insurance, storage and security

• Specie or valuables cover on agreed values with worldwide wearing cover; check pair-and-set clauses.
• Bank or private vault storage for pieces not in use.
• Photographs, laboratory reports and valuations stored separately from the pieces.

Care and maintenance

• Have settings and clasps checked periodically; have pearls restrung as needed.
• Store pieces separately to avoid scratching.

Selling and exit

• Auction, consignment to dealers, or private sale; signed pieces and fully documented stones typically sell more readily.
• Remounting or re-cutting can change value; take specialist advice first.

Red flags

• Reports from unknown laboratories, or reports that do not match the stone.
• Undisclosed treatments, or laboratory-grown stones sold as natural.
• Unclear origin for stones from sanctioned regions.

Questions to ask your advisers

1. How would gifts of jewellery to family members be treated?
2. What do I need to declare when travelling?

Glossary

4Cs

carat, colour, clarity and cut

Kimberley Process

certification scheme for rough diamonds intended to exclude conflict diamonds

Laboratory-grown diamond

a diamond created in a laboratory rather than mined

Signed piece

jewellery bearing the maker's mark of a recognised house

Specialists you may need