60 Fun Facts About Sapphire

Sapphire is a gem variety of which mineral?

The same mineral in red is sold as ruby; almost every other colour is called sapphire.

What score does sapphire earn on the Mohs hardness scale?

Only diamond and moissanite are harder, which is why sapphire ends up on watch faces and barcode-scanner windows.

Gem-quality stones of the same mineral as sapphire, but red, are sold under which name?

The red comes from chromium; the two gems are so closely related that some dealers call rubies 'red sapphires'.

Sapphire is the traditional birthstone for which month?

The month's other associations are more modest: its flower is the aster and morning glory.

Sapphires that are any colour other than blue are known in the trade as what?

They turn up in yellow, orange, green, purple and even colourless, though only the blue ones are what most people picture.

Which two trace elements together produce the classic blue of a sapphire?

The blue appears with as little as 0.01 percent of the pair present, whereas a ruby needs at least 1 percent chromium to turn red.

The name padparadscha comes from Sanskrit words describing the colour of which flower?

The name is from padma ranga; natural, untreated stones of this shade are the most valuable of all the fancy sapphires.

A padparadscha sapphire is prized for which unusual blend of colours?

The variety was originally found in Sri Lanka, though deposits have since turned up in Vietnam and East Africa.

The star-like effect seen in a star sapphire is known by what name?

The stones are cut as smooth domes rather than facets so the star sits near the top under a single overhead light.

The needle-like inclusions that create a star sapphire's star are most often which mineral?

The same titanium dioxide needles give an untreated stone its 'silk'; heating dissolves them and deepens the blue.

A typical star sapphire displays a star with how many rays?

Twelve-rayed stars occasionally occur when two different sets of inclusions line up in the same crystal.

A twelve-rayed star sapphire pairs the usual needle inclusions with platelets of which mineral?

The rutile makes a whitish star and the second mineral a golden one; the two overlap to form twelve rays.

Roughly how much does the famous Star of India star sapphire weigh?

It is almost flawless and unusual in showing a star on both sides of the stone.

The Star of India is on display in which institution?

J. P. Morgan donated it with the rest of a collection assembled for the 1900 Paris Exposition.

The Star of India was stolen in 1964 by a gang whose best-known member went by which nickname?

The thieves climbed in through a bathroom window they had unlocked during opening hours; the gems turned up in a Miami bus locker.

During the 1964 museum heist, the Star of India was the only gem protected by an alarm. Why did it fail?

The stolen stones, valued at over $400,000, also included the DeLong Star Ruby and the Eagle Diamond.

The 423-carat Logan Sapphire is roughly the size of what?

It is set in a brooch with 20 diamonds and is the heaviest mounted gem in the Smithsonian's collection.

The Logan Sapphire takes its name from what?

Rebecca Guggenheim gave the stone to the Smithsonian, then married John A. Logan in 1962 and the gem took her new name.

Which silent-film star bequeathed the 182-carat Star of Bombay to the Smithsonian?

The violet-blue stone had been a gift from her husband Douglas Fairbanks and gave a famous gin its name.

The label of Bombay Sapphire gin carries a portrait of which monarch?

The name nods to the gin and tonic of the British Raj; the 'Sapphire' half honours the Star of Bombay.

The Star of Adam, the largest known blue star sapphire, was found in 2015 in which country?

At 1,404 carats it dethroned the 733-carat Black Star of Queensland, and its name refers to the belief that Adam settled on Adam's Peak.

The Sri Lankan sapphire town of Ratnapura is known by which nickname?

The Logan Sapphire, the Star of India and the Star of Adam are all believed to have come from its mines.

A 733-carat black star sapphire found by a boy in 1938 served his family for ten years as what?

Twelve-year-old Roy Spencer picked it up on a hillside; a Los Angeles jeweller later paid $18,000 for it and cut away 400 carats to reveal the star.

Which singer wore the 733-carat Black Star sapphire on television in 1971?

It appeared on The Sonny & Cher Comedy Hour while on loan to the Smithsonian; the stone has rarely been seen in public since.

Which country became the world leader in sapphire production, thanks to the deposits around Ilakaka?

The Ilakaka rush transformed a tiny village into a boomtown in the late 1990s.

In 1987, which country was the world's largest producer of sapphires?

The country is still the largest source of parti-coloured sapphires showing two or more colours in one stone.

Sapphires from which origin command the highest premium in the gem trade?

The deposits produced for only a short period around 1900, and their velvety blue is instantly recognisable to dealers.

The record auction price per carat for a sapphire, set in October 2015, is roughly how much?

The ring sold for more than $6.7 million in total; the stone was, of course, from Kashmir.

Sapphire has been the official state gem of which Australian state since 1985?

The state also gave its name to the famous 733-carat black star stone found there in 1938.

The prized Yogo sapphires are mined in which US state?

The state produces more gem-quality sapphires than anywhere else in North America and made the stone a state gem in 1969.

Yogo sapphires are typically described as which shade of blue?

The colour comes from trace iron and titanium and holds up under artificial light, a rarity among sapphires.

In the 1980s, Intergem marketed the Yogo as the world's only sapphire guaranteed to be what?

The campaign exposed the fact that around 95 percent of the world's sapphires were being heated to improve their colour.

In 1895 rancher Jake Hoover's cigar box of Yogo stones ended up being appraised by which New York firm?

The appraiser called them the finest precious gemstones ever found in the United States, and the mining rush was on.

In which year did Auguste Verneuil first synthesise blue sapphire?

He had cracked synthetic ruby in 1902 and only turned to blue once chemists showed iron and titanium were behind the colour.

The Verneuil method for growing synthetic sapphire is also known by what name?

Fine alumina powder falls through an oxyhydrogen flame and builds a teardrop-shaped boule on a ceramic pedestal.

The Czochralski process for growing synthetic sapphire was invented in 1916 by a chemist of which nationality?

A seed crystal is slowly pulled out of molten alumina, producing carrot-shaped boules that can weigh up to 200 kg.

In 2014, Apple was reported to be consuming what share of the world's sapphire supply?

The sapphire went into iPhone camera lens covers and fingerprint readers; a plan for full sapphire screens bankrupted supplier GT Advanced Technologies.

Which phone was the first production smartphone with a sapphire screen?

Apple's own sapphire-screen venture collapsed with the bankruptcy of its supplier GT Advanced Technologies.

Sapphire wafers are widely used as a substrate for gallium nitride LEDs of which colour?

The sapphire costs about one-seventh as much as germanium, which helped make LED lighting cheap.

Titanium-sapphire lasers are popular for their unusual ability to do what?

They cover the red and near-infrared and are also easy to mode-lock, which makes them a workhorse for ultrafast pulses.

The Greek word sappheiros, ancestor of 'sapphire', probably originally referred to which stone?

The blue stone we now call sapphire was not discovered until Roman times, so the older word had to mean something else.

According to traditional Hindu belief, wearing a sapphire makes which planet favourable to the wearer?

The planet is known as Shani in Hindu astrology, and blue sapphire is its prescribed gemstone.

Pope Innocent III decreed that a bishop's ring should be pure gold set with what?

The stone was meant to act as a seal of secrets, guarding what a priest 'conceals from the senses of the vulgar'.

Mary, Queen of Scots owned a 'medicinal' sapphire pendant that she used to treat what?

An Italian superstition likewise held sapphires to be amulets against eye trouble and melancholy.

The 104-carat Stuart Sapphire is part of which collection?

James II took it with him when he fled to France in 1688, and it only came back to Britain a century later via a cardinal's mitre.

In 1909 the Stuart Sapphire moved to the back of the Imperial State Crown to make way for what?

It still sits at the back of the 1937 crown worn by Charles III, engraved with a miniature history of the crown.

St Edward's Sapphire is thought to come from the coronation ring of a king who took the throne in which year?

Edward the Confessor was buried wearing the ring; the stone was reputedly removed when his body was moved in 1163.

A colour-change sapphire that looks blue outdoors typically turns which colour under incandescent light?

The effect mimics alexandrite, and synthetic versions are sometimes sold as 'alexandrium', though alexandrite is an entirely different mineral.

Evidence of gemstones being heat-treated to improve their colour dates back at least to which era?

Modern furnaces run at 800 to 1,800 °C for hours or even weeks; untreated stones now sell with laboratory certificates.

Colourless sapphires were once used in jewellery as a substitute for which gem?

Completely colourless corundum is very rare in nature; today the stones are mostly used as accents.

The 510 kg cluster of star sapphires unearthed in Sri Lanka in 2021 was given what name?

The name is a pun: 'serendipity' derives from Serendip, an old name for Sri Lanka.

How much did Roy Whetstine claim to have paid for a 1,905-carat star sapphire in Tucson?

The stone was later appraised at $1,200 per carat, but a reporter found the appraiser had valued an identical-weight stone years earlier.

Sapphire is chemically an oxide of which metal?

The pure oxide is colourless; every sapphire colour comes from a trace of something else in the crystal.

A sapphire is the traditional gift for which wedding anniversary?

A 'sapphire jubilee' is different again: it marks 65 years, as with Elizabeth II's accession in 2017.

Which pale blue sapphire jubilee milestone did Queen Elizabeth II reach in 2017?

She had already passed the diamond jubilee in 2012, and reached platinum in 2022.

Besides jewellery, sapphire is used in watches for which component?

Its Mohs 9 hardness makes it far more scratch-resistant than mineral glass, so it also covers barcode-scanner windows.

What is the best-known colour of sapphire?

The gem also occurs in grey, black and even colourless forms, but the classic stone is the deep blue of the September birthstone.

Which country pioneered the use of single-crystal sapphire in artificial hip joints?

Sapphire is biocompatible and wears extremely slowly against metal, which is what an implant needs.

Which element has been diffused into corundum since 2000 to create padparadscha-coloured stones?

The treatment is done under very high heat, just below the melting point; the earliest results around 2000 were orange stones.

What is the 3,536-carat purple stone discovered near Ratnapura in 2025 called?

It is the largest documented purple star sapphire, from the same Sri Lankan region that produced the 1,404-carat Star of Adam.