Coloured gems: in demand
Experimental feature

Listen to this article

Experimental feature

Whether it is a question of bidding on emerald earrings at a New York auction, buying a ruby ring from a luxury flagship in London, or sourcing loose gems from a dealer in Hong Kong, an independently verified precious stone certificate is now an essential component of a sale within the fine jewellery industry.

Global appetite for coloured gems has soared in recent years and with it the demands of discriminating consumers, who want more knowledge about the cut, colour, weight and carats of their purchases.

The fact that sources of coloured gems are dwindling fast, coupled with a growing preference for natural rather than irradiated, treated or synthetic stones, means the identification – and authentication – services of gemmological experts are sought after.

And the presence of the slip of paper that they are able to provide – or lack of it – can have a big impact on a transaction.

“Now that the market has decided that treated stones are of a lesser value than their untreated counterparts, the absence of a certificate can weigh negatively on price by as much as 30 to 40 per cent,” says Kenneth Scarratt, southeast Asia managing director of the Gemological Institute of America – one of the leading providers of certificates.

“People want to be absolutely sure of what they are buying,” he adds. “Today, you simply cannot sell coloured gems without one. In fact, many buyers require multiple reports for a single stone, all from separate, independent laboratories.”

The value and characteristics of gems are determined in labs through visual analysis, microscopic evaluation, chemical testing and refractive indices.

Afterwards, a report, often containing security features such as a hologram to prevent it being forged or duplicated, is returned alongside the stone to its seller, be it an independent brand or auction house.

Despite certification often being slow and bureaucratic, it is widely accepted as an integral part of a sale.

Gary Schuler, head of the jewellery department at Sotheby’s auction house, says: “It’s part of a package we offer clients that they see as non-negotiable. Many are buying pieces as investments and are aware that treatments potentially dilute the quality of a stone or distort its value.”

He believes the coloured stone certificate trend began about 30 years ago, when the coloured stones market collapsed. Customers lost trust in what they were buying amid a rapid increase in use of sophisticated treating techniques, including the enhancement of emeralds by Colombian drug barons, using a potentially corrosive resin filler.

Provenance became paramount, particularly when public concern grew about blood or conflict diamonds.

“Today, colour and geography significantly affect prices,” says Olivier Reza of fine jeweller Alexandre Reza. “There is a big difference in the price of an emerald from say, Zambia or Colombia, for example.

“Provenance gives a huge premium to stones, even if the stones look virtually identical.”

Mr Schuler believes this also applies to the public’s approach to treatments, saying: “Heating and filling of coloured gems has been around for decades, but these treatments and fakes became harder to detect with the naked eye, so processes to confirm the authenticity of a stone became more commonplace.”

Pierre Rainero, director for image, heritage and style at Cartier, calls the certificate “fundamental”. But he adds that, as well as being the scientific basis for the price of a treated or untreated coloured stone, grading of characteristics is important because aesthetic appeal is as important to a client as monetary value.

“The notions of beauty and charm are linked to the hues, cut and shape of a stone,” he says.

However, there are some in the industry such as Mr Reza who, while asserting the importance of independent analysis of inventories, ponder its increasing reliance on the reports.

“My fear is that some people, by acquiring this piece of paper, stop really appreciating the stone,” he says. “In some ways, it’s becoming a branding conceit, almost a way of artificially creating price premiums.”

And the irony, he says, is that coloured gems – even those with certificates – still sell for considerably less than their colourless counterparts.

“Truly exquisite emeralds, sapphires and rubies are far more difficult to come by than white diamonds. They are the rarest stones in world and should be priced as such.’


Valuation game: The industry’s go-to players

Valuation certificates confirming the quality, rarity and authenticity of a gem are becoming an essential component of any sale, no matter who is buying.

A report from one of the three core companies confirming clarity, colour, cut or weight can elevate the value of the examined precious stone. There are also many smaller firms in the marketplace, including American Gemological Laboratories and GemResearch Swisslab.

Gemological Institute of America

An independent, US-based non-profit organisation that is the world’s largest authority on gemmology. It has experts across the globe. Its reputation is foremost in diamond grading, and its labs have pioneered synthetic detection software to be used by diamond trading bourses. It is also a leading school for independent gemmology degrees.

Gubelin Gem Lab

Established in 1924, this Switzerland-based laboratory was developed internally by jewellery house the Gubelin Company after it recognised the need for a broad and well-founded knowledge of the gemstones it was mounting. Today, it is the leading European destination for the entire industry, specialising in country of origin reports for coloured stones. It now has a second lab in Hong Kong.

SSEF (Swiss Gemmological Institute)

The services offered by SSEF are lauded by industry insiders for being rooted in academic research. The Swiss laboratory is known to focus on identifying the characteristics of loose precious stones, but only to provide characteristics analysis rather than commercial evaluation. It also combats the latest innovations being used to create hard-to-spot synthetics and fakes.

This article was amended on April 2 to reflect the fact that Olivier Reza compared the price of Colombian emeralds with those from Zambia.

Get alerts on Luxury goods when a new story is published

Copyright The Financial Times Limited 2019. All rights reserved.

Follow the topics in this article