Everything you need to know about rubies

The ruby, whose name comes from the Latin "rubeus"meaning"reddish", is one of the most prized gemstones among jewelers for its intense color and symbolic properties. In its finest quality, Ruby is also rarer than diamond.

The history of jewelry is inseparable from this noble gem, due to its quality, which ensures excellent longevity, and the appeal it has aroused among enthusiasts and collectors. Want to know everything about emeralds, their origins, and how their prices have changed? Read our article on the subject! 

History and general characteristics of the ruby

The earliest known sources of ruby mining date back to theAntiquity, especially in Asia, where it was considered the "sun stone" because of its bright color.

The ruby is described as a variety of corundum (aluminum oxide) since the 1800s (before this date, ruby, red spinel and pyrope garnet were all commonly referred to as "carbuncles"), just like sapphire. Their difference lies in the range of their colors: sapphire can be any color of the rainbow, except for red, which is reserved for rubies. This color is due to the presence of chromium with a participation of iron; a determining factor in its value: the brighter and purer the red, the more valuable the ruby. The most sought-after of all is the "pigeon's blood" ruby, a true red with a hint of blue.

Like sapphire, ruby has a hardness of 9 on the Mohs hardness scale, making it extremely scratch-resistant, ranking it second only to diamond. This characteristic explains its strong presence in the jewelry world, since this stone is easily set and can subsequently be worn daily without risk.

Inclusions are common in natural rubies and are often considered a "signature" of their authenticity.

In addition to these well-known characteristics, there are others that are just as fascinating and yet rarely used in jewelry. In particular, the presence of asterisms on certain rubies, which draw a star on the surface of the stone, most frequently with 6 branches, and sometimes up to 12. This phenomenon is due to the interference of light with a large quantity of inclusions called “silks,” which are actually fine needles of rutile (titanium dioxide). This phenomenon is highlighted by the cabochon cut of corundums. Thus, while in jewelry, precious stones are mostly cut with facets, the cabochon cut is necessary to highlight the asterism.

Ruby deposits

Ruby from Myanmar (Burma) 

The most renowned rubies come from Asia, particularly Myanmar (formerly Burma), in the Mogok mines, which extend over 1000km2, and produce the most exceptional rubies, characterized by their "pigeon's blood" color (a bright red with a slight blue tint). However, due to intensive mining, Burmese rubies are disappearing from the market, they have become rare and expensive, which considerably increases their price, especially since the arrival of the military junta in power in 1962, Burma has closed in on itself and access to the production areas has become practically inaccessible. Today, the finest specimens exceed several thousand dollars per carat. 

It should be noted that ruby extraction in this geographical area adapts to the dry and wet seasons.

During the dry season, miners dig thin tunnels ranging from 5 to 30 meters deep. They then enter these tunnels to dig up the earth using a shovel and a bamboo basket.

During the rainy season, when these tunnels are submerged by precipitation, they become unusable. Miners then excavate between these structures, facilitating the natural erosion process by using bamboo to direct the cascading water. The recovered soil is then carefully graded to extract rubies.

Mozambique Ruby

Mozambique's more recently discovered rubies now rival those of Burma in terms of quality and color. Within a few years, Mozambique has established itself as the leading ruby-producing country, producing the majority of rubies used in jewelry and fine jewelry, with a mining area of over 30,000 hectares.

Madagascar Ruby

Known as the leading producer of pink sapphire, Madagascar also produces rubies, the finest specimens of which are highly sought after. Madagascar's rubies range in color from orange-red to purplish-red. 

The major deposits are located in the Andilamena province, northeast of Antananarivo. The majority of rubies in this area are brownish-red to purplish and highly included (they often require treatment).

Ruby from Sri Lanka (Ceylon) 

Sri Lanka (formerly Ceylon) has long been renowned for its sapphires, but it has also been a historical source of rubies, from the same deposits in the Ratnapura region, near Colombo, in the western part of the island. They result from the erosion of ancient mountain peaks and appear as alluvial gravel. This gem-bearing gravel is recovered from riverbeds, cleaned, and then carefully graded.

However, in terms of quality, Sri Lankan rubies tend to have a lighter, pinker red color, tending towards raspberry than those from Burma.

Historical Rubies

• The Rosser Reeves Star Ruby: 138.7 carats, on display at the Smithsonian National Museum of Natural History.

• The DeLong Star Ruby: 100.32 carats, housed at the American Museum of Natural History in New York.

• The Black Prince's Ruby: 170 carats (although it is actually a red spinel), mounted in the British Imperial State Crown.

Synthetic ruby

A synthesis, by definition, is the reproduction of a stone according to its physical and chemical characteristics, with the difference that one is produced by nature and the other by man. Synthetic rubies are created in the laboratory by replicating the natural conditions in which rubies form. Two main methods are used:

1) Verneuil process: synthesis by simple or dry fusion

Developed at the end of the 19th century, this process is used to produce synthetic sapphires and spinels: it is now the cheapest and fastest
Aluminum oxide (dry material) is sprayed and melted using an oxyhydrogen torch and then forms drop by drop at the seed. To obtain the desired color, metal oxides (iron, titanium, etc.) must then be added.

2) Czochralski process: synthesis by pulling

Developed in 1919, this process is used for corundums and spinels. The aluminum oxide (liquid material) is already molten and pulled upwards by the seed (which can be natural or synthetic).

3) Synthesis by anhydrous dissolution

Developed in the 1970s, this process is used for corundum, emerald and quartz, it is one of the longest and most expensive (8 to 12 months, the gem crystallizes by 2mm). Aluminum oxide is mixed with fluxes (allowing the melting temperature to be lowered)

4) Synthesis by hydrothermal dissolution.

This process is used for corundum, emerald, and quartz. The crystals grow in high-temperature (500 degrees) and high-pressure (1000 degrees) water to simulate the natural conditions found underground when crystals are created.

Ruby Treatments

Most rubies are treated to improve their color and clarity. The most common treatments are:

Heating 

Helps enhance color by removing unwanted undertones or intensifying red.

Glassfilling 

Cracks can be filled with lead glass to improve the clarity of the stone. This treatment should be disclosed, as it can affect the durability of the ruby.

A certificate of authenticity issued by an independent gemological laboratory (such as GIA, SSEF or Gübelin) is essential to know the nature and extent of the treatments undergone by the ruby.

Price Evolution

Among colored gemstones, emerald is the second most popular "precious" stone in the market, accounting for 23% of colored stone purchases for jewelry, just after sapphires (49%) and ahead of emeralds (18%). 

Ruby is one of the most expensive gemstones, especially when it exhibits an intense "pigeon's blood" color, good clarity, and an appropriate cut. High-quality unheated Burmese rubies fetch exceptional prices on the market.

The price of rubies varies considerably depending on their quality, geographical origin and the treatments they have undergone. The finest specimens today exceed several thousand dollars per carat, as illustrated by the comparison between a ruby from Thailand of 8.22 carats which sold for 13k USD/carat (107.95k USD), against another Burmese of 7 carats which was sold for 408.4k €/carat (2.9M €) or a factor x30, illustrating the appreciation of the quality for a ruby.

Below is a graph showing the price comparison of Burmese pigeon blood rubies by weight, which demonstrates the appreciation of rarity (the greater the weight, the rarer and therefore more expensive it is). A notable record is the ruby Crimson Flame sold for USD 1.2M per carat, a total of 18M USD in 2015.

Discover our other articles on precious stones:
Everything you need to know about sapphire
Everything you need to know about emeralds

Find our entire collection of ruby jewelry: 
Ruby jewelry

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