Rubies are red precious gemstones formed from corundum, an aluminum oxide mineral. Ruby is known for its high rarity and value, its substantial hardness of 9 out of 10 on the Mohs scale, and for being the birthstone for July.
A ruby gets its redness from trace elements of chromium, which absorb light wavelengths of all colors except red. Corundum gems of any other color are known as sapphires. While there are many colors and types of sapphires, rubies come in fewer varieties because they must, by definition, be red.
Saying that, rubies can display varying hues and tones of red depending on their place of origin, as well as other distinctive attributes. We’ve compiled a list of the nine most notable types of rubies, with information about their history, characteristics, and value.
1. Burmese Rubies
Burmese rubies, considered the best rubies in the world, come from Myanmar, also known as Burma. The rarest and finest gemstones are characterized by their soft, velvety luster and vivid, pigeon blood red color.
In the ruby trade, the term “pigeon blood” refers to a specific type of red, a pure and intense hue with a hint of blue or purple. Though most Burmese rubies aren’t pigeon blood rubies, most pigeon blood rubies are Burmese rubies.
The Mogok Valley region is especially famed for yielding exquisite rubies, including the 25.59 carat weight Sunrise Ruby. This stunning gem, deemed “a unique treasure of nature” by the Swiss Gemological Institute, sold for $32.42 million at auction in 2015.
Myanmar’s smaller rubies are thankfully more affordable, though Burmese gems still command a premium compared to other rubies available in the consumer market. Fine quality specimens can sell for more than white diamonds of the same carat weight.
2. Thai Rubies
Thai rubies originate predominantly in Thailand, especially from the Chanthaburi-Trat mining district in the country’s southeast. Some stones marketed as Thai ruby are actually from the Pailin area, located across the border in neighboring Cambodia.
High iron content is a typical Thai ruby characteristic. The iron traces produce a darkening effect, which is why Thailand’s rubies are often a darker, more garnet-like red than the brighter, more intense red associated with rubies from Myanmar. Some gems have purplish or brownish overtones.
A Thai ruby generally has greater clarity and less fluorescence than a Burmese ruby, which is also due to higher iron content. This means that a Thai ruby is less likely to exhibit the warm, velvety glow displayed by many Burma rubies.
While Thailand’s ruby mines have been largely exhausted, you can still find Thai ruby stones in circulation, and the country remains a major center for the cutting, polishing, and trading of rubies imported from other locations.
3. Mozambique Rubies
Since their discovery in 2008, Mozambique rubies have surged in prominence. Now with multiple mines operating over the ruby-rich deposits in the country’s northeast, Mozambique has become a major supplier of ruby to the international market.
Mozambique yields quality as well as quantity. Its top grade material approaches the fineness of traditional sources like Myanmar. Mozambique rubies range from orangy-red to purplish-red to red, with some exhibiting the coveted pigeon blood coloring.
Some Mozambique rubies have prominent internal fractures, requiring treatment to close the fractures before sale. However, regardless of origin, most rubies are treated in some way to improve their color and/or clarity. Untreated stones fetch significantly higher prices.
One such untreated Mozambique ruby is the world’s most expensive ruby, and also its most expensive non-diamond gemstone. The magnificent Estrela de Fura, a 55.22 carat ruby of vivid pigeon blood color, sold at auction in 2023 for $34.8 million.
4. Madagascar Rubies
Madagascar rubies were first discovered in the 1990s, with additional deposits being unearthed in the 2000s and 2010s. Madagascar now supports several prominent mining regions, mostly concentrated in the north-central part of the country.
The island of Madagascar broke away from Africa some 160 million years ago, now lying directly off the coast of Mozambique. As a result of this geological closeness, rubies from the two countries often show similar characteristics.
For instance, Madagascar ruby runs a similar color spectrum to Mozambique: pinkish-red to orangy-red to red. Pigeon blood and deep red stones can be found, with some exhibiting strong fluorescence that gives them an enchanting glow under sunlight.
More distinctive to Madagascar’s rubies are mineral inclusions like monazite crystals and rounded zircons. These features, not common in Mozambique rubies, help in their identification and highlight Madagascar’s unique gemological profile.
5. Indian Rubies
Indian rubies are sourced primarily from the southern parts of the country, particularly the states of Karnataka and Tamil Nadu. India’s ruby mining dates back centuries and is part of the country’s rich gemological heritage.
Rubies from India tend to be opaque rather than transparent, making them more suited for cabochons than faceted gemstones. Some regions produce transparent gems, in hues from pinkish-red to purplish-red. Others produce star rubies.
On the whole, Indian rubies are less esteemed than those from the other locations on this list. India is far more renowned for its beautiful sapphires, and its now-depleted Golconda diamond mines that produced stones of pristine diamond clarity.
However, with the increasing global demand for rubies, India continues to be a notable player in the ruby market. Though the quality of Indian rubies varies, they come with historical significance and charm, and usually at a more affordable price point.
6. Star Rubies
Star rubies display asterism, or the star effect, a rare phenomenon that causes some gemstones to exhibit a star-like pattern on their surface when illuminated. In rubies, asterism is typically caused by needle-like rutile inclusions within the stone.
A star ruby must be cut into a cabochon, rather than faceted, to best showcase its asterism. The quality of the star – its sharpness, symmetry, contrast, and visibility to the naked eye – significantly influences the gem’s value.
Another notable feature of star rubies, apart from the entrancing star, is their color intensity. Star rubies often have deeper, more saturated color than faceted rubies. They’re mostly opaque, though some feature minor translucency.
A high quality star ruby should exhibit strong, evenly distributed red color, overlaid with a distinct white or silvery-white star. Stars are most often six-rayed, but can occasionally show twelve rays. This is known as a double star ruby.
7. Untreated Rubies
Most rubies are treated to improve their color and/or clarity, while untreated rubies are those that haven’t undergone any appearance-enhancing treatments. Untreated stones with good color and clarity are typically more expensive.
Heat-treated rubies are heated to high temperatures, which can enhance their color while dissolving inclusions. Heated rubies are widely accepted in the market, as this heating process mimics natural conditions that occur within the Earth.
In another prevalent treatment, the fractures within a ruby are filled with lead glass to reduce the appearance of cracks. However, the resulting glass-filled ruby is less valuable than a heat-treated or untreated ruby.
Untreated ruby stones are highly valued for their natural beauty and high scarcity. A ruby that doesn’t rely on treatments to enhance its looks is both a rare geological treasure and a symbol of status and authenticity.
8. “Pink” Rubies
“Pink ruby” is a misnomer in the United States. By most modern gemological classifications, including those of the Gemological Institute of America (GIA), a ruby is defined as a corundum gemstone with a dominant red hue.
Then, what is “pink” ruby? The term is mostly used in countries where the line between ruby and pink sapphire is less strict. In Sri Lanka, for instance, pink corundum gems are considered rubies, though in the US they’d be pink sapphires.
In other cases, a ruby may be described as “pinkish” if it displays a pink overtone. A pinkish-red ruby is still a ruby, because its dominant hue remains red. The same applies to purplish-red, brownish-red, and orangy-red rubies.
However, as pink is a paler shade of red, differentiating between a true ruby and a particularly deep pink sapphire can be tricky. To accurately pinpoint a gem’s color, GIA evaluates it against a set of comparison or master stones.
9. Lab-Grown Rubies
Lab-grown rubies, also known as lab-created or synthetic rubies, are chemically and physically identical to natural rubies. They’re created or “grown” in laboratories using methods like flame fusion or the hydrothermal process.
Though lab-grown rubies possess the same attractive color and hardness as natural rubies, they come at significantly lower prices. Their color can also be customized to individual preferences by varying the ruby’s chromium levels.
Another key aspect of lab-created rubies is their uniformity. Unlike natural rubies, which often have unique inclusions or color variations, synthetic rubies tend to display consistently high clarity and evenly distributed color.
While it’s straightforward for gemologists to identify lab-grown rubies, to the untrained eye, they’re usually indistinguishable from natural rubies. That’s why it’s smart to get any ruby assessed by an impartial professional before you buy.