Gemstone pricing follows no single formula. A stone's value depends on the intersection of rarity, colour quality, size, origin, and market demand. Some gemstones consistently reach prices that rival or exceed diamonds on a per-carat basis. The following five species regularly command the highest prices at auction and in the wholesale trade.
1. Ruby (Corundum)
Fine Burmese rubies, especially those from the Mogok Valley, are the most expensive coloured gemstones in the world. The most desirable colour, known in the trade as "pigeon blood red," is an intense, slightly purplish red with strong fluorescence. In 2015, the "Sunrise Ruby" (25.59 carats, Burmese, unheated) sold at Sotheby's for $30.42 million, which is over $1.18 million per carat. High-quality Burmese rubies above 5 carats are rarer than equivalent-sized diamonds.
2. Blue Sapphire (Corundum)
Kashmir sapphires, mined from a single deposit at an altitude of 4,500 metres in the Himalayas, set the standard for blue sapphire colour. The deposit was effectively exhausted by the early 1900s, making Kashmir sapphires among the most sought-after gemstones at auction. The "Blue Belle of Asia" (392.52 carats, Sri Lankan) sold for $17.3 million in 2014, but Kashmir sapphires of even 10 carats regularly exceed $200,000 per carat.
3. Emerald (Beryl)
Colombian emeralds from the Muzo and Chivor mines define the ideal emerald colour: a vivid, slightly bluish green with medium tone. Unlike rubies and sapphires, emeralds are expected to contain inclusions, which the trade poetically calls "jardin" (garden). The "Rockefeller Emerald" (18.04 carats, Colombian) sold for $5.5 million in 2017. Zambian emeralds have grown in market acceptance, though Colombian stones still command the highest premiums.
4. Alexandrite (Chrysoberyl)
Alexandrite displays a dramatic colour change: green in daylight, red under incandescent light. First discovered in Russia's Ural Mountains in the 1830s, fine alexandrites showing strong colour change are extraordinarily rare. Brazilian alexandrites above 5 carats with strong change can reach $50,000 to $70,000 per carat. Russian origin stones at the same quality level command even more.
5. Padparadscha Sapphire (Corundum)
Named after the Sinhalese word for lotus blossom, padparadscha sapphires display a delicate pink-orange colour that sits precisely between pink sapphire and orange sapphire. Sri Lanka produces the most prized examples. Fine padparadschas above 5 carats are almost impossible to find on the open market and regularly sell for $20,000 to $50,000 per carat at auction.
For any high-value gemstone purchase, laboratory certification from an independent lab is essential. The difference between a $5,000 stone and a $500,000 stone often comes down to details that only trained gemologists with proper equipment can verify.
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