Loose natural faceted gemstones in orange, pink, purple, blue and green, including pear, oval, heart and cushion cuts

Untreated Rubies

Untreated rubies are rubies (red corundum, Al2O3, colored by chromium) whose color and clarity are exactly as they came from the ground, with no heating or any other treatment. Most rubies on the market are heated to improve their color and clarity, so stones that show their natural, unheated color are much less common and are valued by collectors.

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Gemstone guide

Untreated Rubies

About untreated ruby

Heating is a stable, accepted treatment, but an unheated ruby keeps features that heat would change, such as intact rutile silk and unaltered crystal inclusions, which tell the story of how the stone grew. Unheated rubies come from many of the same sources as heated ones, including Madagascar, Tanzania, Mozambique and Myanmar, and only a small share of each mine's production is fine enough to sell without treatment.

Did you know?

The Sunrise Ruby, a 25.59-carat Burmese stone with lab reports showing no signs of heating, sold at Sotheby's Geneva in 2015 for about $30 million, then a world auction record for a ruby.

How to recognise unheated ruby

Under magnification, unheated rubies often show fine, unbroken rutile needles and sharp-edged crystal inclusions; heating tends to dissolve the needles into dotted lines and leaves crystals with melted-looking halos. Only a gem laboratory can confirm the absence of heat with certainty, but these clues are a good guide.

Caring for untreated ruby

Ruby is hard and tough and has no cleavage. Clean it with warm soapy water and a soft brush, and avoid ultrasonic cleaning if the stone has visible fractures.

Every ruby is natural and untreated, and each listing gives its weight, size and origin, with photos of the actual stone.