60 Fun Facts About Ruby

Ruby is a red variety of which mineral?

Every other gem-quality colour of the same mineral is called sapphire, so rubies are sometimes dubbed red sapphires.

Which element gives a ruby its red colour?

About one percent of the aluminium ions replaced by it is enough to turn the crystal red.

Ruby is the traditional birthstone for which month?

Garnet, January's stone, is usually a deeper, less pink red.

What is the hardness of ruby on the Mohs scale?

Among natural gems only diamond and moissanite are harder.

The word ruby comes from the Latin 'ruber', meaning what?

It is one of the traditional cardinal gems with amethyst, sapphire, emerald and diamond.

What name is given to the brightest, most valuable shade of ruby red?

Stones of that colour command a large premium over rubies of otherwise similar quality.

What is the chemical make-up of ruby?

The pure mineral is colourless; only impurities give it colour.

What are the needle-like rutile inclusions found in all natural rubies called?

Gemologists use them to tell natural stones from synthetics; a ruby with none may have been treated.

What optical effect do 'star rubies' display?

Light reflecting off the oriented needle inclusions produces a three- or six-pointed star, so these stones are cut as cabochons.

At what wavelength does ruby fluoresce, adding to its red glow?

That same emission is what a ruby laser amplifies into coherent red light.

In the United States, a red-family gem that falls below a minimum colour saturation is sold as what?

The distinction only arose in the 20th century and is still debated.

Which valley in Upper Myanmar was for centuries the world's main source of rubies?

Mong Hsu took over as the main mining area in the 1990s.

Which African country became the top source of gem-quality rubies after a 2009 discovery?

Its Montepuez mine reportedly produced about 10 million carats in 2022.

Which is the only country in mainland Europe with naturally occurring rubies?

Found near Prilep, they have a distinctive raspberry colour.

Rubies from which territory are said to be among the oldest in the world, at about 3 billion years?

The Aappaluttoq mine south of Nuuk opened in 2017 but was later suspended for poor production.

What is the most common treatment applied to rubies?

Temperatures around 1,800 C remove purple tinge and needle inclusions; untreated stones command a large premium.

What material is used to fill fractures in low-grade rubies to make them fit for jewellery?

The process involves cleaning with hydrogen fluoride and two rounds of heating.

Which red gemstone is often found alongside rubies and was long mistaken for them?

The finest red examples now fetch prices approaching all but the best rubies.

The Black Prince's Ruby in the Imperial State Crown is actually what?

Such stones were once called 'balas rubies'; the impostor mineral was only chemically distinguished from ruby in the 18th century.

Which English king is said to have worn the Black Prince's Ruby at Agincourt in 1415?

Legend says the Spanish king Peter of Castile gave the stone to the Black Prince in 1367.

How much does the Black Prince's Ruby weigh?

It is about 4.3 cm long and probably came from Badakhshan in modern Afghanistan.

What is the Sunrise Ruby named after?

The 25.59-carat pigeon-blood stone was mounted by Cartier between two heptagonal diamonds.

For how much did the Sunrise Ruby sell at auction in Switzerland in May 2015?

At the time it was the most expensive coloured gemstone ever sold.

Which ruby holds the record as the most valuable ever sold at auction?

Its name means Star of Fura, after the mining company that found it in southern Africa.

What happened to the Liberty Bell Ruby, the largest mined ruby in the world, in 2011?

The sculpted stone has never been recovered.

Whose 8.24-carat ruby ring broke the price-per-carat record in 2011?

Christie's sold her whole jewellery collection that December, including a ruby necklace that also fetched millions.

The 138.7-carat Rosser Reeves Ruby is famous for what feature?

The advertising mogul who donated it to the Smithsonian in 1965 carried it as a lucky charm and called it 'his baby'.

In which country was the Rosser Reeves Ruby mined?

Reeves liked to claim he bought it at auction in Istanbul; he actually acquired it through New York dealers.

The 23.1-carat Carmen Lucia Ruby at the Smithsonian was mined in which region in the 1930s?

Businessman Peter Buck donated it in memory of his late wife.

Who built the world's first working laser, using a synthetic ruby, in 1960?

He fired it up at Hughes Research Laboratories on 16 May 1960, and the prototype still works.

What colour of light does a ruby laser produce?

It lases at 694.3 nanometres in pulses typically about a millisecond long.

Which French chemist announced commercial-scale synthetic ruby production by flame fusion in 1903?

By 1910 his laboratory had 30 furnaces and was making gems by the hundredweight.

Who made the first synthetic rubies in 1837 by fusing potash alum with a colouring element?

Fremy and Verneuil made artificial ruby from barium fluoride and alumina fifty years later.

What tell-tale flaws can magnification reveal in a flame-fusion synthetic ruby?

A ruby with no imperfections at all is itself suspected of being artificial.

Besides jewellery, where are hard synthetic rubies used in mechanical devices?

They also serve as scanning-probe tips in coordinate measuring machines.

What misleading trade name has been used for red tourmaline?

'Balas ruby' was the old term for the red impostor stone; gem labs discourage both names.

In traditional Hindu astrology, ruby is the gemstone of which heavenly body?

Wearing it is believed to win the favour of Surya, leader of the nine Navagraha.

Around 200 BC rubies were carried westward from China along which trade route?

In India and China rubies decorated armour, scabbards and harnesses, and were buried under foundations for luck.

In L. Frank Baum's original novel, what were Dorothy's magic shoes made of before the film made them ruby?

The change showed off the new three-strip Technicolor process; screenwriter Noel Langley is credited with the idea.

How many pairs of the original ruby slippers from The Wizard of Oz are known to survive?

One pair was stolen from the Judy Garland Museum in Minnesota in 2005 and recovered by the FBI in 2018.

How much did the once-stolen pair of ruby slippers fetch at auction in December 2024, fees included?

That made them the most valuable movie memorabilia ever sold at auction.

In Marvel comics, the ruby 'Godstone' turned John Jameson into which creature?

He found the stone on the Moon and it grafted itself to his chest.

What did 17th-century fakers burn to colour the foil placed under imitation rubies?

Imitation rubies go back to Roman times.

In which year were spinels first chemically distinguished from true rubies?

Both contain aluminium and oxygen coloured by the same element, but the impostor also has magnesium.

Which of these US states has produced a few rubies?

Montana, South Carolina and Wyoming are the others.

By 1907, roughly how much synthetic gemstone was Verneuil's laboratory producing per year?

Most synthetic rubies are still made by flame fusion because it is cheap.

Apart from diamond, which natural gem is harder than ruby on the Mohs scale?

It sits somewhere between corundum at 9 and diamond at 10.

Which European country is listed among historic ruby sources, alongside Thailand, Afghanistan and Japan?

Post-war finds added Madagascar, Mozambique, Nepal, Pakistan, Tajikistan, Tanzania and Vietnam to the list.

Azad Jammu and Kashmir has proven ruby reserves worth up to how much, yet only one mine as of 2017?

Lack of investment left just the Chitta Katha mine operating; Afghanistan mines rubies at Jegdalek.

Greenland's Aappaluttoq ruby mine, opened in 2017, was suspended for what reason?

Most rubies mined there were heavily fractured and had to be heated with borax powder.

With what chemical is rough ruby cleaned before the lead-glass filling process?

A first heating without fillers follows, probably around 900 °C, before a second heating with lead glass powder.

Which businessman donated the 23.1-carat Carmen Lúcia Ruby to the Smithsonian in memory of his wife?

Set in a platinum ring with diamonds, the Burmese stone shows a richly saturated red with exceptional transparency.

Why were Dorothy's silver shoes changed to ruby for the 1939 film The Wizard of Oz?

The magical footwear became a driving element of the plot in its new red form.

Who created the Ruby programming language, conceived in 1993 in Japan?

Known as 'Matz', he wanted an object-oriented scripting language better than Perl or Python.

What other name was proposed for the Ruby programming language before Ruby was chosen in 1993?

Matsumoto picked Ruby in a chat with Keiju Ishitsuka, partly because a colleague's birthstone was ruby.

Which web framework is credited with surging interest in the language around 2005?

By 2000 Ruby was already more popular than Python in Japan, and the first English book Programming Ruby appeared that year.

Ruby Bridges desegregated which New Orleans elementary school on November 14, 1960?

She was six; white parents pulled their children out and only Boston-born teacher Barbara Henry agreed to teach her.

Which Norman Rockwell painting, published in Look in 1964, depicts Ruby Bridges walking to school?

Bridges recalled that seeing the crowds she thought it was Mardi Gras.

Which child psychiatrist counselled Ruby Bridges weekly and later wrote The Story of Ruby Bridges?

He donated the 1995 book's royalties to the Ruby Bridges Foundation.

Which Indianapolis institution opened a $6 million exhibit in 2007 pairing Bridges with Anne Frank and Ryan White?

'The Power of Children: Making a Difference' includes an authentic re-creation of her classroom.