Ruby

Ruby is red corundum, Mohs hardness 9 — the only red member of the corundum family. Its value turns less on size than on origin and treatment: heating is an accepted norm, while lead-glass filling is another matter entirely, and worth far less. Here is the whole picture — from identity and reasons to buy, to the insider truths, the market reality and care.

About Ruby

Ruby is red corundum (aluminium oxide), coloured by traces of chromium; within corundum, only the red is called ruby — every other colour is a sapphire. It is the same mineral as sapphire, parted only by the trace elements it carries. The more chromium, the deeper the red; yet chromium, as the crystal forms, also draws in fractures and inclusions. So a natural ruby that is at once large, red and clean is born rare — rarer, grade for grade, than a diamond. Exactly where pink ends and red begins is a line each laboratory still draws a little differently.

Why Choose a Ruby

Ruby is July’s birthstone and the stone of the 15th and 40th wedding anniversaries — a symbol of love and strength, and at hardness 9, hard-wearing enough for daily wear. Red is our most primal colour — blood, fire, heartbeat, passion; the name itself comes from the Latin ruber, meaning red. In Chinese gift-giving, where meaning matters, that true red reads as festive and momentous — one of the few coloured centre stones you can give without a misstep. The finest colour is called “pigeon’s blood”: a pure, faintly purplish deep red set against strong red fluorescence, seeming to glow from within under sunlight — the grade you collect and pass down.

History & Famous Stones

Ruby has been called the “king of gemstones” (Sanskrit ratnaraj) since antiquity, and the pigeon’s-blood reds of Mogok, Burma have been pursued by emperors and Mughal royalty for centuries. Its most famous stones tell the whole story of that red:

• The Sunrise Ruby: 25.59 carats, Burmese pigeon’s blood, sold at Sotheby’s Geneva in 2015 for US$30.4 million — the most expensive ruby, and the most expensive coloured gemstone (fancy diamonds aside) ever sold at auction, at a record price per carat.
• The Rosser Reeves Star Ruby: 138.7 carats, a Sri Lankan star ruby with a sharp, well-defined star — one of the most famous star rubies in the world, now in the Smithsonian.

The Truth About Ruby

With ruby, origin and treatment matter more than size: heating is an accepted norm, while lead-glass filling is another thing altogether, and worth far less.

• Origin and treatment outweigh carats. Rubies from the marble of Mogok, Burma — high chromium, low iron, pure red, strong fluorescence — set the world’s standard; Mozambique now yields reds to rival them at a gentler price. For the very same colour, a single origin report can move the price several-fold.
• Heating is not filling. Honestly declared, heating is legitimate trade; what you must tell apart is “heated only” versus “heated and filled”.
• Guard most against lead-glass filling (composite ruby). Fractured, near-worthless rough is flooded with lead glass to pass as a clear “ruby”; the value is a world apart, and the stone fears acid, heat and ultrasonic cleaning.
• Unheated, with a top origin report, is auction territory — the premium can multiply.

Ruby on the Market

What is sold as “ruby” is not one thing but several — natural, heated, lead-glass filled, synthetic, imitation — and prices can differ a hundredfold; the certificate is what settles it.

Type	Traits	Price	How to tell
Natural · unheated	Natural colour + origin report	Highest	Report reads “no heat”
Natural · heated	Standard, more even colour	High	Report reads “heated”
Lead-glass filled	Big fractures filled, see-through	Low	Loupe shows gas bubbles + blue-purple flash
Synthetic (flame-fusion)	Too perfect, too red	Very low	Curved growth lines (natural shows angular colour banding)
Imitation	Spinel / garnet / glass, matched by colour	Varies	Certificate, refractive traits

The “Black Prince’s Ruby” in the British crown is in fact a spinel; “pigeon’s blood” now has defined colour standards from Gübelin and Lotus, yet every seller on the street will call their stone one — a label, in the end, is not a certificate.

Before You Buy

Before buying a ruby, first ask “is it filled?”, get a certificate that states treatment and origin, and remember that a filled ruby must never meet ultrasonic cleaning or acid.

• Open with a single question: “Is it filled?” Heating is acceptable; lead-glass filling is far cheaper, and another matter entirely.
• Insist on a certificate, and read the treatment and origin closely.
• “Pigeon’s blood” — trust the certificate, not the sales pitch.
• A filled ruby must not go into an ultrasonic cleaner or touch acid — remind your jeweller before any repair or cleaning.
• Keep this in mind: a large, clean natural ruby is inherently rare and will not be cheap; a “big ruby” at an unbelievable price usually has a story behind it.