Danielle Saudino

Education

In-depth articles on the gemstones, mines, markets, and histories that define the world of rare gems.

Diamonds

15 articles

Diamonds

Red Diamonds

Among the rarest diamonds on Earth — the GIA has graded roughly 1,000 natural red diamonds in total, but fewer than thirty true red diamonds, with no secondary hue, are estimated to exist worldwide.

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Diamonds

Fancy Colored Diamond Grading

How the GIA evaluates the hue, tone, and saturation that define a fancy color diamond's value.

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Diamonds

Purple Diamonds

Among the most underappreciated of the fancy colors, with color origins that remain scientifically debated.

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Diamonds

Orange Diamonds

Pure orange diamonds are among the scarcest in the GIA's classification system.

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Diamonds

Blue Diamonds

Type IIb stones carrying trace boron — the scientific explanation behind the world's most expensive gems per carat.

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Diamonds

Yellow Diamonds

The most accessible entry point into the fancy color world — and, at their vivid peak, spectacularly valuable.

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Diamonds

Green Diamonds

Nature's most patient work — formed over millions of years of radioactive exposure deep within the Earth.

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Diamonds

Where Fancy Color Diamonds Come From

A geological and geographical guide to the world's great fancy color diamond deposits.

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Diamonds

The Fancy Color Diamond Price Index

How the industry tracks fancy color diamond prices — and what two decades of data reveal about which colors appreciate.

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Diamonds

Understanding Diamond Rarity

One in 10,000 carats displays fancy color. One in 25,000 displays intense color. Here is how rarity is actually quantified.

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Diamonds

True Face-Up: Why Carat Weight Isn't Everything

Two diamonds of identical carat weight can look dramatically different in size. Shape, cut depth, and proportions determine what you actually see.

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Diamonds

Investing in Fancy Color Diamonds

How fancy color diamonds compare to other luxury assets — and what decades of market data reveal about their strengths and limitations as investments.

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Diamonds

How to Evaluate a Fancy Color Diamond at Auction

Pre-auction analysis requires reading beyond the estimate. Here are the key factors that determine whether a stone is a bargain or a trap.

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Diamonds

Type IIa Diamonds

The chemically purest diamonds on Earth — less than 2% of all gem diamonds — prized for an optical quality described as 'an internal light.'

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Diamonds

When Grading Labs Fail: Scandals, Bribery, and Fraud

The laboratories that grade the world's diamonds are trusted as arbiters of value — but they have not always been worthy of that trust. A history of misconduct, from the 2005 GIA bribery scandal to counterfeit reports in India.

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Colored Gemstones

11 articles

Colored Gemstones

Kashmir Sapphires

The world's most coveted sapphires — from a remote Himalayan deposit that has not been commercially mined in over a century.

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Colored Gemstones

Paraíba Tourmalines

The neon-blue tourmalines from Brazil that rewrote the rules on what colored gemstones could be worth.

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Colored Gemstones

Brazilian Alexandrites

The stone that changes color by day — and why fine examples now rival the finest rubies and sapphires.

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Colored Gemstones

Australian Black Opals

The world's most spectacular play-of-color phenomenon, found almost exclusively in a small town in New South Wales.

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Colored Gemstones

Burmese Rubies

The world's finest rubies come from Myanmar's Mogok Valley — and have for over a thousand years.

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Colored Gemstones

Heat, Oil & Other Treatments

What the gem trade does to stones before they reach you — and why disclosure and certification matter.

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Colored Gemstones

Diamond Provenance and Origin Certification

Why a laboratory-confirmed country of origin can double or triple a stone's value — and how the science of origin determination actually works.

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Colored Gemstones

Colombian Emeralds

The world's finest emeralds come from three ancient mining districts in the Colombian Andes — and have been prized since pre-Columbian times.

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Colored Gemstones

Caring for Colored Gemstones

Each gemstone has its own personality — and its own vulnerabilities. A practical guide to cleaning, wearing, and storing colored stones.

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Colored Gemstones

Opals of the World: Ethiopian vs Australian, Black vs Crystal

Opal is the most geographically and genetically diverse of all gemstones. From the ancient sedimentary opals of Lightning Ridge to the hydrophane volcanic opals of Ethiopia, understanding where an opal comes from is essential to understanding how it behaves.

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Colored Gemstones

Selecting a Black Opal: Quality Factors and Buying Guide

Black opal is the rarest and most valuable variety of opal, and evaluating one requires a different vocabulary than any other gemstone. A practical guide to body tone, brightness, pattern, and the art of choosing the right stone.

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Origins & History

14 articles

Origins & History

The Argyle Diamond Mine

The world's most important source of pink and red diamonds — and why its closure in 2020 reshaped the market forever.

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Origins & History

The Golconda Diamond Mines

The birthplace of the world's most legendary diamonds — Koh-i-Noor, Hope, and Regent among them.

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Origins & History

Famous Diamonds Throughout History

From the Koh-i-Noor to the Cullinan — the stones that shaped empires, inspired myths, and defined an art form.

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Origins & History

Famously Unlucky Gems: A Darker Side to Jewels

The curses, tragedies, and mysteries that shadow some of the world's most beautiful stones.

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Origins & History

The Argyle Pink Diamond Tender

For nearly four decades, the world's most important pink diamonds were sold through an invitation-only sealed-bid process unlike anything else in the gem trade.

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Origins & History

Gems of the Stars: Famous Diamonds Worn by Celebrities

From the Tiffany Yellow Diamond to La Peregrina Pearl — the legendary stones that crossed from royal collections and auction houses onto the world's most photographed necklines, fingers, and ears.

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Origins & History

The Great Jewelry Houses

From Cartier to JAR — a guide to the most celebrated fine jewelry maisons, their iconic designs, and the founders and artisans who shaped them.

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Origins & History

Influential Women Jewelry Collectors

From Gertrude Vanderbilt Whitney to Bridget Rooney Koch — the women whose collections redefined modern notions of luxury and connoisseurship.

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Origins & History

Pulled: When Gems Are Withdrawn from Auction

The world's most spectacular stones sometimes vanish from the catalogue before the gavel falls. Here is what happens — and why — when auction houses pull headline lots.

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Origins & History

Diamonds and Deception: Notable Gem Fraud Cases

From lab-grown diamond swaps to a $3 million uncut diamond heist and the collapse of a luxury jewelry empire — the most newsworthy gem fraud cases of the past fifteen years.

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Origins & History

Stewards of the Wealth: Botswana's Ministry of Mining

The officials who have overseen Botswana's mineral wealth have shaped one of the most successful resource-governance stories in modern history. A chronicle of the ministry and the ministers who have guided it.

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Origins & History

Botswana and De Beers: A Fifty-Year Partnership

The Debswana joint venture — born in 1969 from the discovery of diamonds in a newly independent nation — has been called the most successful mining partnership in history. Its story spans discovery, negotiation, and a transformative 2023 deal.

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Origins & History

How Diamonds Transformed a Nation: Botswana's Development Story

From one of the poorest countries on earth to upper-middle-income status in a single generation — the story of how Botswana used diamond wealth to build a nation, and why it became a model for resource governance worldwide.

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Origins & History

Brazil's River Diamonds: Alluvial Treasures of the Jequitinhonha

Long before Botswana or South Africa, Brazil was the world's diamond capital. The stones were found not in deep mines but in riverbeds — washed from ancient kimberlites and deposited in the gravel of the Jequitinhonha and its tributaries.

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