Colored gemstones are incredibly unique and rubies are some of the most spectacular examples of that originality. While technically made of corundum crystal, the same as sapphires, rubies have achieved their own classification within the gemstone world. And part of understanding the core of rubies is recognizing the specific meanings behind the terms “natural” and “untreated” when used to describe the precious gemstone.
The majority of rubies and ruby jewelry on the market today are described as “natural.” This label means that a ruby was created by the geological processes within the earth and is not man-made.
Rubies were one of the first gemstones to be successfully synthesized in the laboratory and several types of lab-grown rubies are available. Synthetic rubies can be made by a number of commercial methods including the flame fusion (Verneuil), flux growth, hydrothermal, and pulling (Czochralski) processes.
Synthetic ruby has the same chemical composition and structure as natural ruby. However, depending on the different means of synthesis, lab-grown rubies can be distinguished from their natural counterparts by trained gemologists who look for specific features under magnification.
When a ruby is listed as natural, that title does not necessarily mean it is untreated as well. A “natural ruby” could still have been subjected to treatments intended to improve its clarity and color.
A treated ruby can still be categorized as natural because the description of natural only indicates that the ruby is not lab-grown. An untreated ruby however, is a natural ruby that has not undergone any treatments whatsoever.
Treated rubies are often inferior ruby crystals that are heated and chemically altered to drastically improve their visual appeal and saleability. The inherent value and rarity of a heated ruby is thus significantly lower than a natural, untreated ruby.
Attitudes differ regarding the practice of treating rubies, but the most important factor is always the full disclosure of any treatments or enhancements a ruby may have undergone.
Not all gemstones that are called “rubies” are actually ruby. The term “ruby” is sometimes applied as a trade name for other types of gemstones. However, these gems do not share any of the physical characteristics or chemical properties of true rubies.
For reference, below is a list of common gem trade names and their actual gemstone type.
As we continue to discuss the essential knowledge on rubies, understanding Ruby Crystals & Chemistry is next.