Red, with a little more going on
Ruby is famous for being red, but that's hardly the end of the story. Rubies can lean raspberry, purplish, scarlet, or deep crimson. Some look almost illuminated from within. And the ones with a little character—an unusual cut, a visible inclusion, or a star that moves in the light—are especially exciting to me.
Ruby and sapphire are the same mineral
Ruby is the red variety of corundum, made primarily of aluminum oxide. Sapphire is the name for gem-quality corundum of other colors. Chromium is responsible for ruby's red. Both ruby and sapphire measure 9 on the Mohs hardness scale, making them excellent choices for scratch-resistant jewelry, though a sharp impact can still damage them.
Star rubies: a real star made of light
Some rubies contain extremely fine, oriented inclusions, often needles of rutile. When the stone is cut as a properly oriented cabochon—a smooth dome—a concentrated light source can produce a six-rayed star. This phenomenon is called asterism. The star seems to travel across the surface as you move the stone. It's not painted or carved on; it's an optical effect made possible by the crystal's internal features. I love star rubies. They're a perfect example of inclusions creating something spectacular.
Why some rubies seem to glow
Chromium can also cause red fluorescence under ultraviolet light. In some rubies, particularly those with less iron, fluorescence adds to their vivid appearance in daylight. It's part of why certain stones look so alive. Not all rubies fluoresce to the same degree, and lighting makes a difference.
Where rubies come from
Rubies form in certain metamorphic and other geological environments. Myanmar's Mogok region is historically celebrated for ruby, and Mozambique has become another major source. Rubies are also found in Sri Lanka, Thailand, Vietnam, and Madagascar. Their chemistry, inclusions, and colors can offer clues to their geological history.
Natural ruby versus treated ruby
Many natural rubies are heated to improve color or clarity. Other rubies may be fracture-filled with glass or treated in more extensive ways. These treatments are not equivalent, and they can substantially change durability, value, and care requirements. Natural describes a stone's origin; it does not automatically mean untreated. For a significant ruby purchase, reliable treatment information matters.
A gemstone people have prized for centuries
Ruby has been admired across cultures for centuries and is July's traditional birthstone. Its red color has been associated with passion, power, and vitality. Historical gemstone names can be confusing, though: some famous 'rubies' in royal treasures turned out to be red spinel. Even royalty couldn't always tell their red stones apart before modern gemology.
The rubies I want to work with
A perfectly transparent ruby can be magnificent. But I also love a lively raspberry color, an unusual rose cut, or a star ruby that makes you tilt your head and chase the light. I handcraft each piece around the individual natural gemstone, rather than making every stone conform to the same design. The stone's quirks are often the best part.
Every Mettle by Abby piece is handmade and one of a kind. Explore the other gemstone guides and see what's new.
