Ten Ruby Gemstone Facts (July Stones)
Ten Ruby Gemstone Facts
1. Ruby Is the Red Variety of Corundum
Ruby is a variety of the mineral corundum (aluminum oxide). All other colors of gem-quality corundum are classified as sapphire, not ruby.
What makes ruby different is the presence of chromium, which gives it its red color.
2. Rubies Rank 9 on the Mohs Hardness Scale
Ruby is extremely durable, ranking 9 out of 10 on the Mohs scale. Only diamond is harder.
This makes ruby one of the best gemstones for rings and daily-wear jewelry.
3. The Finest Rubies Have a Color Called “Pigeon Blood”
In the gem trade, the most prized ruby color is often described as “pigeon blood red,” meaning a rich red with a slight bluish undertone.
This term is especially associated with top-quality rubies from Myanmar (Burma).
4. Some Rubies Glow Under UV Light
Many rubies fluoresce strongly under ultraviolet light due to their chromium content. In some stones, this fluorescence can make the ruby appear even more vivid in daylight, boosting its visual appeal.
5. Ruby Can Form a Star Pattern Called Asterism
Some rubies display a six-rayed star when cut as a cabochon. This phenomenon is called asterism and is caused by tiny needle-like inclusions of rutile aligned within the crystal structure.
These stones are called star rubies.
6. Rubies Are Often Heat-Treated to Improve Color and Clarity
Most rubies on the market have been heat-treated, a long-accepted practice that can improve color and reduce the visibility of inclusions.
Untreated rubies with fine color are rare and can command very high prices.
7. The World’s Most Famous Rubies Often Turn Out Not to Be Rubies
Several historic “rubies” in royal collections were later identified as red spinel, not ruby.
One famous example is the Black Prince’s Ruby in the British Imperial State Crown, which is actually a spinel.
8. Ruby Inclusions Are So Common They Have Their Own Nickname
Rubies commonly contain mineral inclusions, tiny fractures, or rutile silk. These natural internal features are sometimes called a ruby’s “fingerprints.”
While inclusions can reduce clarity, they are also used by gemologists to help identify origin and detect treatments.
9. Myanmar (Burma) Has Produced Some of the Most Valuable Rubies Ever Found
The Mogok region of Myanmar has historically produced rubies considered among the finest in the world, known for their saturated color and strong fluorescence.
High-quality Burmese rubies have set major auction records.
July Gemstones ~ Ruby Quiz
As you may know Ruby is one of the gemstones of July together with Carnelian, another reddish gem. Here is a fun trivia quiz about this beautiful gemstone.
No email is required - your score and the answers will come up here after you hit the Submit button :).
