July Birthstone - Ruby

If you are born in July, you are very fortunate to have as your birthstone the famed Ruby; it’s one of the world’s most coveted colored gems. In my opinion, whether you have a July birthday or not, owning a beautiful ruby is a rare and special experience.

Ruby is one variety of the corundum mineral species, which also includes sapphire.

In its purest form, the mineral corundum is colorless. Trace elements that become part of the mineral’s crystal structure cause variations in its color. Chromium is the trace element that causes ruby’s red, which ranges from an orangy red to a purplish red.

The strength of ruby’s red depends on how much chromium is present—the more chromium, the stronger the red color. Chromium can also cause fluorescence, which adds to the intensity of the red color.

Ruby can form in two environments. One is marble, the other is basalt.

Marble has low iron content, so rubies that originate in marble (called “marble-hosted” by gemologists) lack iron. Because of this, many have an intense red color.

?In addition, rubies found in marble typically fluoresce red under ultraviolet light—even the ultraviolet light in sunlight. Fluorescence can make a ruby’s color even more intense and increase its value.

Rubies can also be found in basalt rocks. Rubies from these sources can have higher iron content, which can make the rubies darker and less intense in color. Higher iron content in the chemical makeup of a ruby can also mask the red fluorescence, eliminating that extra glow of red color seen in marble-hosted rubies.