The World Within Ruby: A Guide to Color, Clarity, and Origins

From July's warmth and legendary jewels to the microscopic world—reflections inspired by my studies at Gübelin.

If summer had a gemstone, ruby would feel like a natural choice. Its vivid red brings to mind July's heat, late sunsets, and the energy of long summer days.

Ruby is July's birthstone and the traditional gemstone for a 40th wedding anniversary. The same red can celebrate a birthday or mark a love that has deepened over four decades. (GIA: July Birthstone)

A Gemstone Fit for Kings—and the Sun

Our fascination with ruby began long before modern jewelry.

In Sanskrit, ruby was known as Ratnaraj, meaning “king of precious stones,” and Ratnanayaka, “leader of precious stones.” These names reflect the extraordinary regard in which it was held. Gübelin also introduces ruby through its ancient name, Ratnaraj, and celebrates it as a symbol of passion and love. (Gem-A: Ruby and Sapphire, Gübelin: The Precious Ruby)

Within India's traditional Navaratna, or “nine gems,” ruby represents the Sun and occupies the center of the arrangement. This cultural and astrological association gives its red another dimension: a connection with light, vitality, and the central presence of the Sun. (The Metropolitan Museum of Art: Gems and the Indian Tradition)

Ruby's history also lives through the people who wore it.

In 1937, Maharaja Digvijaysinhji of Nawanagar commissioned a magnificent ruby and diamond necklace from Cartier. Its graduated ruby fringe and geometric diamond details brought together Indian royal splendor and Art Deco design. (Christie's: The Nawanagar Ruby and Diamond Necklace — 点击查看实物图 / view photos of the piece)

Three decades later, ruby became part of another celebrated jewelry story. In 1968, Aristotle Onassis gave Jacqueline Kennedy Onassis a pair of Van Cleef & Arpels ruby and diamond ear pendants as a wedding present. Diamond leaves suspended detachable cabochon ruby drops—a personal expression of ruby's enduring connection with love. (Christie's: Jacqueline Kennedy Onassis's Ear Pendants — 点击查看实物图 / view photos of the piece)

That fascination continues in the auction room. In 2015, the 25.59-carat Sunrise Ruby sold at Sotheby's Geneva for more than US$30 million, setting the ruby auction record at the time. Gübelin's account recalls its laboratory's description of the stone as “a unique treasure of nature.” (Gübelin: The Sunrise Ruby, Guinness World Records: Ruby Auction History)

These stories give ruby a rich human history. My studies at Gübelin encouraged me to look further: What creates that red? Why do some rubies seem to glow from within? And what can their microscopic features tell us?

These questions also shape how I think about ruby at DHARIN.

What Makes a Ruby Red?

Ruby is the red variety of corundum, the same mineral species as sapphire. Pure corundum is colorless; trace elements introduce its remarkable range of colors.

In ruby, the defining element is chromium. Small amounts replace aluminum within the crystal structure, changing how the material absorbs light and producing its characteristic red. Gübelin explores this relationship between chemistry and beauty in its ruby feature, Red Majesty. (Gübelin: Red Majesty)

Laboratory-grown ruby is also corundum, with essentially the same chemical, physical, and optical properties as natural ruby. Its distinguishing feature is how it forms: in a controlled production environment rather than through natural geological processes. (GIA: Ruby)

Different growth environments can produce the same gemstone material while leaving different clues inside it.

How Geological Setting Influences Color

Chromium gives ruby its red, but other trace elements help shape its appearance. The geological environment influences which of those elements enter the crystal.

Marble-hosted rubies typically contain relatively little iron. With less iron suppressing their red fluorescence, some display a particularly lively glow in daylight.

Basalt-related rubies, including those from certain deposits in Thailand and Cambodia, generally contain more iron. Iron affects light absorption and suppresses red fluorescence, so some of these rubies appear darker and show less of that luminous red glow. (GIA: Ruby Description)

“Basalt-related” deserves a little explanation. It does not necessarily mean the ruby crystallized in basalt. Basaltic magma can carry previously formed crystals from deep within the Earth to the surface. The rock transporting a gemstone may therefore differ from its original growth environment. (GIA: Colored Stones from the Deep)

These relationships help explain broad tendencies. They do not determine the beauty of every individual stone.

Beyond “Pigeon Blood”: Understanding Ruby Color

“Pigeon blood” is one of the most celebrated expressions in the ruby trade. It is also a trade name without a single internationally standardized definition, so the laboratory using the term matters. (Gübelin: Deeply Inspired 2023, pp. 34–35)

What Does Gübelin Mean by “Pigeon Blood”?

Gübelin describes an intense, saturated, evenly distributed red, allowing a very slight violet tint, together with strong fluorescence under ultraviolet light.

Its explanation connects this inner glow with chromium and low iron content. Geographic origin does not determine eligibility: rubies from different countries can qualify if they meet the laboratory's criteria. (Gübelin: Deeply Inspired 2024, “Pigeon Blood”)

Crimson Red and Pigeon Blood Red: The Fluorescence Difference

Under Gübelin's criteria, both Crimson Red and Pigeon Blood Red require natural rubies with rich, homogeneous red color, high transparency, no eye-visible inclusions, and no indications of heating or other treatment. Faceted stones should also display lively internal color reflections.

The key distinction is their fluorescence under ultraviolet light.

A ruby qualifying as Pigeon Blood Red shows a distinct red fluorescent effect. If all the other requirements are met but fluorescence is less pronounced, Gübelin may describe the stone as Crimson Red.

Crimson Red therefore does not apply to every ruby with weak fluorescence. It is a specific designation with demanding color and quality requirements. (Gübelin: Deeply Inspired 2023, pp. 34–35)

Where Does the Inner Glow Come From?

Fluorescence occurs when a material absorbs energy and emits light.

In suitable rubies, chromium produces red fluorescence when excited by ultraviolet light. Because daylight contains ultraviolet radiation, fluorescence can contribute to a ruby's appearance outside the laboratory as well. Gübelin describes this phenomenon as the source of ruby's remarkable inner glow. (Gübelin: Red Majesty)

This helps explain why two rubies with similar body colors may feel different when seen in changing light.

Three Ways to Look at Ruby Color

For anyone discovering ruby, three observations offer a useful starting point:

• Hue: Does the red lean slightly toward purple or orange?
• Tone: How light or dark does the stone appear?
• Saturation: How vivid is the color? Does it appear pure, or somewhat muted?

Ruby also exhibits pleochroism. Its absorption of light varies with polarization and crystal direction, producing red to purplish-red shades in one direction and orangy-red shades in another. Gem cutters consider this when choosing how to orient a stone. (GIA: Ruby Quality Factors)

Then look at the whole gem. Does its color stay lively as you turn it? Are there noticeably pale or dark areas? Do you enjoy its appearance in the lighting where you will wear it?

A celebrated name offers context. Observation helps you discover your own preferences.

Inside Ruby: Silk, Light, and Microscopic Fingerprints

Under magnification, ruby can reveal slender needles, tiny crystals, and patterns formed during growth.

Gübelin's exploration of gemstones' “inner worlds” offers a compelling way to understand these features. Inclusions can provide evidence about a gemstone's formation, geographic origin, and possible treatment. (Gübelin: Inner Worlds)

Rutile Silk and a Softer Glow

One of ruby's best-known internal features is rutile silk: fine, needle-like inclusions of rutile.

These needles can occur in zones, patches, or clouds. They scatter light, creating a soft shimmer that can combine with fluorescence to give some rubies a particularly gentle, luminous appearance. (Gübelin: Inner Worlds, “Rutile Needles”)

Their amount and distribution matter. Dense inclusions can reduce transparency, while significant fractures may affect durability. Clarity is therefore about how internal features influence the entire stone, rather than simply whether inclusions are present. (GIA: Ruby Quality Factors)

Natural and Laboratory-Grown Growth Clues

Both natural and laboratory-grown rubies can contain inclusions.

Certain hydrothermally grown rubies show distinctive chevron-shaped growth patterns, while some flux-grown rubies contain wispy, veil-like features. These observations become useful when interpreted alongside other evidence. (GIA: Ruby Inclusion Chart, GIA: Inclusions in a Flux-Grown Ruby)

The question is not simply whether a stone has inclusions. What matters is what they are, how they occur, and what the complete combination of features reveals.

What Can a Ruby Tell Us About Its Origin?

For natural ruby, geographic origin identifies where it formed. Geological history adds a deeper timescale.

Some ruby deposits in Mozambique and Madagascar are associated with ancient mountain-building events hundreds of millions of years ago. Some Asian deposits, including those in Myanmar, are linked to the more recent Himalayan mountain-building system. Formation ages vary by deposit. (GIA: Gems Formed in Metamorphic Rocks)

Gübelin emphasizes the importance of characteristic inclusions and reference stones in investigating origin. Differences in geological conditions can leave patterns that become meaningful through careful comparison. (Gübelin: Inner Worlds, “The Scientific Significance”)

Origin determination can also require trace-element analysis and other laboratory evidence. Some stones share characteristics with material from several locations, making an inconclusive result the appropriate conclusion. (GIA: Geographic Origin Determination of Ruby)

For laboratory-grown ruby, the relevant story is its growth process. Its internal features record a controlled environment while retaining ruby's essential gemological properties.

Five Remarkable Ruby Auction Stories

Exceptional natural rubies have made auction history through rare combinations of color, size, quality, and provenance. These five sales offer a glimpse into that world.

Figures are published sale prices, including buyer's premium, rather than hammer prices alone. Dollar equivalents are approximate where indicated. Record descriptions refer to the time of each sale.

One distinction is worth keeping clear: Crimson Flame is the name of an individual ruby; Crimson Red is a trade designation used by Gübelin.

These results document the collecting history of extraordinary natural specimens. For everyday appreciation, the pleasure remains much more personal: the color, the light, and how a jewel feels when worn.

DHARIN's Perspective: Beauty Informed by Knowledge

At DHARIN, my studies at Gübelin inform the way I think about color, clarity, and the relationship between gemstones and light.

The qualities that interest me are tangible: a red with depth and vitality, transparency that allows light to travel through the stone, and a cut that gives its color room to be seen. These are the qualities I want to explore through laboratory-grown ruby.

The study of natural ruby provides a rich visual and scientific reference. It helps me understand how color, internal structure, and cutting work together to create a gem's individual character.

Choosing laboratory-grown ruby also reflects an interest in how gemstones are made. It offers a route to ruby that does not require extracting the crystal from a natural ruby deposit. A complete environmental assessment would still need to consider raw materials, production energy, cutting, and transport; laboratory growth alone does not establish a product's overall footprint.

For me, thoughtful jewelry begins with attention: to the beauty we see, the material we wear, and the information we share.

Ruby draws us in with its red. Understanding it gives us more to see.

Shop DHARIN's Lab-Grown Ruby Edit

If this guide has you looking closer at ruby, our lab-grown pieces are built around the same qualities discussed above — saturated color, clean transparency, and cuts that let the red do the talking. Explore the Ruby Halo Stud Earrings, the Ruby Tennis Bracelet, or browse the full Lab-Grown Gemstones collection.

This article combines personal learning reflections with publicly available gemological sources. References to Gübelin's terminology and criteria are educational and do not imply that DHARIN's laboratory-grown rubies have received those designations, a Gübelin grade, or endorsement by Gübelin.

Photos: Jason D, Hiya Jewelry, Ömer Evren and Ian Talmacs via Unsplash.