Pigeon’s Blood? Royal Red? Understanding Six Major Ruby Grading Systems

If diamonds are forever, rubies are passion. For centuries, rubies have symbolized vitality, love, and strength and no other gemstone evokes such emotional intensity through color alone. Today, debates around Pigeon’s Blood Ruby Grading show just how much meaning the world attaches to the finest shades of red.

Auction records show that a ruby certified as an unheated stone described as “pigeon’s blood” by leading international labs fetched HK$4.3 million at a 2019 Hong Kong auction.

Yet, despite unanimous agreement on its natural origin and quality, the labs used slightly different wording in the color description section of their reports:

• GRS: Vivid Red (Pigeon’s Blood)
• Gübelin: Red, with a comment that the trade calls this “pigeon blood red”
• SSEF: Red of strong saturation, also with a comment noting the trade term “pigeon blood red”

This raises a key question: Why do different labs describe the same ruby differently?

The answer lies in the fact that there is no globally unified ruby color grading system. Each laboratory applies its own definitions, shaped by history, scientific criteria, and trade usage.

Below, we break down six influential ruby color grading systems used internationally.

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Pigeon’s Blood Ruby Grading: How International Labs Define the Finest Red

I. GRS and Pigeon’s Blood Ruby Grading

II. Gübelin and Its Ultra-Strict Ruby Color Grading

III. SSEF and Its Definition of Pigeon’s Blood Ruby Grading

IV. LOTUS Gemology and Ruby Color Grading

V. GUILD Gem Lab and Ruby Color Grading

VI. NGTC Laboratory and Ruby Color Grading

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I. GRS and Pigeon’s Blood Ruby Grading

1. GRS and the Origin of “Pigeon’s Blood”

The GemResearch Swisslab (GRS), founded in 1996 by Dr. A. Peretti, is one of the most influential gemological laboratories in Switzerland. Known for its work with top international auction houses, GRS has shaped how the trade and collectors evaluate ruby color.

GRS introduced the term “Pigeon’s Blood Ruby” in 1996 to describe rubies with a very specific and highly desirable color quality. In 2015, GRS officially registered “GRS-type Pigeon’s Blood Ruby” as part of its certification language, aiming to provide greater consistency in the market.

Unlike the GIA system, which uses hue, tone, and saturation as quantifiable parameters, GRS applies descriptive color terms. Its ruby color descriptions progress as follows:

• Pinkish-red
• Purplish-red
• Red
• Deep Red
• Pigeon’s Blood

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2. The Evolution of “Pigeon’s Blood” Standards

The phrase “Pigeon’s Blood” originated in Burma’s Mogok mines. Local traders compared the vivid red color of certain rubies to the eyes of local pigeons, which are strikingly crimson. These rare gems quickly earned a reputation for commanding significantly higher prices, reinforcing the prestige of the term.

• Early definition: Only rubies from Burma with the right saturation were considered “Pigeon’s Blood.”
• 2001 revision: GRS broadened the definition. Any ruby—regardless of origin—could qualify if it showed a vivid red color, strong saturation, minimal secondary hues, and medium to strong fluorescence under 365nm UV light.
• 2018 update: GRS further refined its grading. It introduced two new sub-categories to narrow the range of acceptable “Pigeon’s Blood” colors, and it explicitly excluded overly dark rubies often called “black Pigeon’s Blood” in the trade.

This progressive refinement shows how Pigeon’s Blood Ruby Grading has become stricter over time, ensuring only the finest colors meet the standard.

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3. Main Certificate vs. Supplementary Certificate

In today’s market, sellers often refer to GRS main-certificate Pigeon’s Blood or GRS supplementary-certificate Pigeon’s Blood. While both qualify as Pigeon’s Blood rubies, their differences lie in color tone and fluorescence.

• Main certificate (Type 1): Described as vivid red (GRS-type Pigeon’s Blood). These rubies typically lean toward a slightly pinkish-red hue and show strong fluorescence, a trait associated with higher chromium content.
• Supplementary certificate (Type 2): Described as vivid red with an asterisk. These stones usually appear as pure red without the pinkish overtone. They show weaker or no fluorescence, often attributed to higher iron content.

Gemologists generally agree that the presence or absence of fluorescence explains these distinctions. However, GRS certificates themselves do not state trace element concentrations.

In terms of value, the price gap between main and supplementary certificates is usually modest. Collectors who prefer a bright, glowing red may choose the main certificate, while those who favor a deeper, pure red may prefer the supplementary certificate.

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4. “Black Pigeon’s Blood” and Other Categories

Another common trade expression is “black Pigeon’s Blood,” referring to rubies described on GRS reports as vivid red to deep red. These stones are darker in tone but not completely black; under good lighting, they still reveal a strong, attractive red. Importantly, this label is a market nickname, not an official GRS grading term.

GRS also uses the category Intense Red to Vivid Red for rubies that may lean slightly purplish or pinkish, though their dominant hue remains red.

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5. The Short-Lived “Scarlet” Term

In 2014, GRS briefly introduced the term “Scarlet” to describe untreated Mozambican rubies that displayed a vivid red color very close to Pigeon’s Blood. On certificates, this appeared as vivid red (scarlet).

However, this label was short-lived and only applied to reports issued between 2014 and 2015. Today, “Scarlet” is no longer in use, and rubies once classified as such are now primarily of historical interest.

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Conclusion

The concept of Pigeon’s Blood Ruby Grading reflects both gemological science and market tradition. While GRS established the term, its meaning has evolved, becoming more precise with each update.

• Pigeon’s Blood rubies remain the benchmark for the finest red.
• Main and supplementary certificates highlight subtle differences in fluorescence and tone.
• Trade nicknames like “black Pigeon’s Blood” or historical terms like “Scarlet” add cultural flavor but are not official grades.

For collectors and buyers, understanding these distinctions helps in making informed decisions. Ultimately, whether one prefers a glowing vivid red or a rich, pure red comes down to personal taste, as both fall under the elite category of Pigeon’s Blood rubies.

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II. Gübelin and Its Ultra-Strict Ruby Color Grading

1. About the Gübelin Gem Lab

Founded in 1923, Gübelin Gem Lab is one of Switzerland’s most established gemological institutions. In the international jewelry world, it enjoys a reputation for professionalism, rigor, and authority. Notably, many auction-grade and top-collection rubies are sent to Gübelin for certification, and its reports are widely regarded as both reliable and market-relevant.

2. Ruby Color Levels in the Market

In practice, the jewelry market often uses layered terms to describe ruby colors, such as:

• Hot Pink
• Orange/Pinkish Red
• Red
• Vivid Red
• Vibrant Red
• Pigeon Blood Red

Among them, Pigeon Blood Red is generally considered the highest trade designation. However, it is important to emphasize that these names are trade terms rather than an official, fixed six-level grading scale published by Gübelin.

3. Gübelin’s Strict Definition of “Pigeon Blood Red”

To qualify as Pigeon Blood Red under Gübelin’s standards, a ruby must meet several exceptionally strict requirements:

• Hue range: strictly between pure red and slightly purplish red, with only a minimal trace of purple allowed.
• Color conditions: highly saturated color with balanced tone, combined with medium to strong red fluorescence.
• Clarity: tiny fissures may be tolerated, but the stone must not display eye-visible opaque zones or prominent dark inclusions.
• Color uniformity: overall consistent color, with only minor light leakage permitted.

Because these conditions are so demanding, only an extremely small fraction of rubies can qualify for Gübelin’s Pigeon Blood Red grading.

4. The 2015 Updated Standard

In 2015, Gübelin and SSEF (Swiss Gemmological Institute) jointly refined and harmonized their trade terminology for ruby color. The updated definition of Pigeon Blood Red included:

• A pure red hue;
• No obvious secondary colors such as blue or brown, with only minimal purple tolerated;
• A distinct red fluorescence visible under strong UV light.

Although the grading does not formally depend on geographic origin, in practice, most rubies that meet Gübelin’s Pigeon Blood Red criteria still come from Myanmar. Cases from other sources remain rare.

5. How It Appears on Certificates

Even when a ruby qualifies for Gübelin’s Pigeon Blood Red grading, the Color field in the report usually lists it simply as “red.”
Only in the Comments section does Gübelin cautiously note:

“This colour variety of ruby may also be called ‘pigeon blood red’ in the trade.”

This wording underscores two important points:

• Pigeon Blood Red is not a proprietary Gübelin invention but an established trade term.
• Gübelin merely acknowledges in its comments that the gemstone’s color may be referred to as Pigeon Blood Red within the trade.

6. Market Value and Significance

Compared with other laboratories that may apply the term more broadly, Gübelin enforces an ultra-strict threshold. Therefore, rubies that achieve Pigeon Blood Red grading from Gübelin are perceived as exceptionally rare and carry significant market prestige.

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📌 Summary

• Gübelin is one of the world’s most respected and rigorous colored gemstone laboratories.
• Its Pigeon Blood Ruby Grading standards are so strict that very few rubies qualify.
• Compared with other reports, Gübelin’s certification of Pigeon Blood Red holds higher credibility and scarcity value.

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III. SSEF and Its Definition of Pigeon’s Blood Ruby Grading

1. About SSEF

Founded in 1974, the Swiss Gemmological Institute (SSEF) is one of Switzerland’s three major gemological laboratories. As an independent, non-profit scientific research institution, SSEF is widely recognized for its objectivity and rigorous methodology.
Its certificates frequently appear in high-profile auctions at Sotheby’s and Christie’s, and the laboratory is respected internationally for its precise and credible gemstone assessments.

2. SSEF and the “Pigeon Blood” Standard

In 2015, SSEF partnered with Gübelin to release a standardized definition for ruby color, aiming to unify the high-end market’s understanding of Pigeon Blood Red and minimize confusion caused by differences in laboratory grading.

As a result, SSEF’s core criteria for Pigeon Blood Red largely align with Gübelin’s:

• Hue: Strictly pure red, allowing only a minimal trace of purple.
• Color conditions: High saturation with balanced tone.
• Fluorescence: Strong red fluorescence under UV light.
• Clarity: Only tiny fissures are acceptable; no prominent inclusions that impact appearance.
• Color uniformity: Even distribution of color throughout the stone.

3. Differences from Gübelin

While SSEF’s Pigeon Blood Red criteria are essentially consistent with Gübelin’s, the laboratories differ slightly in terminology:

• Gübelin notes in the comments section: “pigeon blood red may be used in the trade”.
• SSEF prefers to use the term “red of strong saturation” internally to describe the highest-quality pigeon blood rubies.

This difference reflects subtle variations in academic phrasing and reporting style, but it does not affect the consistency of the actual grading between the two labs.

4. Market Significance

Thanks to the joint standards established by SSEF and Gübelin, the market now enjoys a more unified reference for Pigeon Blood Red. Like Gübelin, SSEF’s grading is considered among the strictest color standards in the ruby trade.
Therefore, rubies certified as Pigeon Blood Red by SSEF also carry significant rarity and credibility in auctions and high-end collections.

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📌 Summary

• SSEF is one of Switzerland’s three most authoritative gemological laboratories, known for independence, non-profit status, and scientific rigor.
• Its Pigeon’s Blood Ruby Grading standards largely mirror Gübelin’s, with the primary difference being the terminology “red of strong saturation”.
• In the high-end jewelry market, SSEF certificates, like those from Gübelin, represent the highest authority for Pigeon Blood Red rubies.

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IV. LOTUS Gemology and Ruby Color Grading

1. About LOTUS Gemology

LOTUS Gemology, located in Bangkok, Thailand, is a specialized laboratory focused on colored gemstone analysis.
Compared to internationally recognized labs such as GRS and Gübelin, LOTUS provides more refined assessments of gemstone color and origin characteristics. Its reports receive high attention from advanced colored gemstone collectors and auction houses.
Thanks to its innovative grading system, the laboratory is often referred to as the “fashion leader in gem grading,” particularly for its expertise in identifying ruby color and origin features.

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2. LOTUS Ruby Color Grades

LOTUS classifies ruby colors into five primary types, ranging from light to deep tones:

Pastel

• This color falls between pink and red, with a soft, low-saturation hue.
• It typically describes jewelry-grade rubies rather than high-end collector pieces.

Hot Pink

• Displays a slight blue undertone and strong red fluorescence.
• Observed in both rubies and pink-toned corundum.
• According to LOTUS experts, this color commonly originates from the Himalayan mining belt as well as Mozambique and Tanzania in East Africa.

Fuchsia

• Named after the flower, Fuchsia shows a more intense reddish-purple tone than Hot Pink.
• Found in rubies from Myanmar, Sri Lanka, Mozambique, Vietnam, Afghanistan, and Tanzania.
• Its saturation is higher, appearing visually closer to true red.

Pigeon’s Blood

• This represents the top-tier color in LOTUS’s ruby grading system.
• The hue is pure red with noticeable fluorescence, reminiscent of a traffic signal’s bright red light.
• While this color can appear in rubies from various locations—including Thailand’s Mong Hsu, the Mebs mine, Vietnam, Mozambique, and Tanzania—not all rubies from these regions meet the Pigeon’s Blood standard.
• Its vivid, uniform color makes it highly sought after in auctions and among collectors.

Royal Red

• This deep red hue exceeds Pigeon’s Blood in darkness. High iron content suppresses fluorescence, resulting in a darker appearance.
• Mainly sourced from Mozambique, Thailand, Cambodia, Kenya, and Madagascar.
• LOTUS first introduced this category to describe deep red rubies with low fluorescence.

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3. Summary

LOTUS Gemology’s unique grading system provides a detailed classification of ruby colors and their origin characteristics.
From Pastel to Royal Red, its five-level grading helps collectors and jewelers accurately identify ruby color quality while offering a valuable reference for the high-end market.
Among these, Pigeon’s Blood stands as the pinnacle of ruby color within LOTUS’s system, commanding exceptional market recognition and collector value.

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V. GUILD Gem Lab and Ruby Color Grading

1. About GUILD Gem Lab

GUILD Gem Lab, established in 1980, is an international laboratory specializing in colored gemstone analysis.
It became the first colored gemstone laboratory to establish a branch in mainland China while earning international recognition, making its reports highly authoritative and widely referenced in the Asian colored gemstone market.
The laboratory bases its grading system on the Munsell color theory and supports it with actual ruby color reference stones, ensuring that evaluations are both scientific and quantifiable.

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2. GUILD Ruby Color Grades

GUILD classifies ruby colors into four main grades, ranging from lighter to deeper tones:

• Medium: Medium saturation and brightness, suitable for describing jewelry-grade rubies.
• Intense: Higher saturation, noticeably rich in color, yet not at the top-end level.
• Vivid: High saturation and brightness, representing the color standard for premium rubies.
• Deep: Darker red, visually deeper than Vivid while maintaining good luster.

Within GUILD’s grading framework, Pigeon’s Blood is not an independent official grade but represents the most ideal top-tier color within the Vivid Red category. Rubies of this color achieve exceptional brightness and saturation, making them highly sought-after in the high-end market.

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3. Definition of “Pigeon’s Blood”

GUILD defines Pigeon’s Blood rubies according to the following criteria:

• The color must be natural and unenhanced;
• The ruby must reach the Vivid Red grade, exhibiting high brightness and saturation;
• GUILD does not restrict recognition by geographic origin, although most rubies meeting this standard come from Myanmar’s Mogok region;
• Certificates typically list the ruby as Vivid Red* with a footnote: Also called Pigeon’s Blood in the trade
  (commonly referred to as Pigeon’s Blood in the gemstone trade).

It is important to note that the gemological community has not established a universal standard to differentiate rubies from pink sapphires. GUILD gemologists consider Light Red outside the ruby color range because its lower saturation does not meet the standard required for high-quality rubies, reflecting the laboratory’s strict approach to top-tier ruby color evaluation.

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4. Summary

GUILD Gem Lab is the first international colored gemstone laboratory to establish a branch in mainland China while earning global recognition.
Its ruby color grading system is scientific, rigorous, and supported by actual color reference stones, making color assessments quantifiable and reliable.
Within this system, Pigeon’s Blood represents the top-tier color within Vivid Red, serving as a benchmark for high-end ruby color standards, with strong market recognition and collectible value.

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VI. NGTC Laboratory and Ruby Color Grading

1. About NGTC

NGTC (National Gemstone Testing Center) is China’s authoritative gemological laboratory, specializing in the scientific identification and testing of gemstones.

NGTC was among the first international gem labs to establish a branch in mainland China and gain international recognition. Its reports carry high authority and are widely referenced in the domestic colored gemstone market.
The laboratory developed its ruby color grading system based on color science principles, using visual reference stones to ensure a scientific and quantifiable assessment of ruby colors.
Compared with international laboratories, NGTC primarily focuses on the natural origin and color grading of rubies, and it currently does not provide official ruby origin certificates.

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2. NGTC Ruby Color Grades

NGTC grades ruby colors along two dimensions: Hue and Saturation/Brightness.

Hue Classification

• Red (R): Standard red, representing the most typical ruby color.
• Purplish Red (pR): Red with a slight purple tint, visually leaning toward red-violet.
• Orange Red (oR): Red with a slight orange tint, visually leaning toward red-orange.

Note: Hue classification primarily describes visual color perception and does not directly reflect the gem’s chemical composition or trace elements.

Saturation/Brightness Levels

• Red: Basic red with moderate saturation.
• Intense Red: Higher saturation and more vivid color, yet below the top-tier standard.
• Vivid Red: High saturation and brightness, representing the top-quality ruby color. It closely resembles the international Pigeon’s Blood standard, though NGTC’s criteria are slightly less strict.
• Deep Red: Darker red with lower brightness, still maintaining good luster.

Color Notation Method

NGTC uses a “Saturation + Hue” approach to describe ruby colors. For example:

• A ruby with orange-red hue and deep-red saturation is labeled Deep Orange Red.
• For standard red hues, only the saturation term is used, such as Vivid Red or Intense Red.

In practice, NGTC combines both saturation and hue for a comprehensive color description, providing a more accurate representation of a ruby’s visual color.

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3. Comparison with International Laboratories

• NGTC focuses on verifying ruby naturalness and grading color.
• It does not provide official origin certificates, unlike laboratories such as Gübelin, SSEF, or LOTUS.
• While NGTC’s Vivid Red corresponds closely to the international Pigeon’s Blood standard, international criteria also consider fluorescence, clarity, and optical characteristics, which are stricter than NGTC’s visual-based evaluation.

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4. Summary

NGTC has established a domestic ruby color grading system in China that combines hue and saturation for a scientific, quantifiable assessment of ruby color.
Vivid Red represents the top-tier ruby color in the NGTC system and serves as a domestic reference for the international Pigeon’s Blood standard.
Overall, NGTC’s grading system offers collectors, jewelers, and enthusiasts a clear, authoritative local reference, helping to identify and compare ruby colors while distinguishing domestic standards from stricter international benchmarks.

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Key Takeaways for Buyers

• GRS: First to codify “Pigeon’s Blood,” widely used in Asian markets.
• Gübelin & SSEF: Strictest standards, most respected in auctions; very few rubies meet their pigeon’s blood criteria.
• Lotus: Added “Royal Red” to describe darker stones.
• GUILD: Practical, Munsell-based, trade-oriented definitions.
• NGTC: China’s national standard; top tier equals vivid red.

👉 Important correction to common misconceptions:

• Not every lab agrees on what qualifies as pigeon’s blood.
• Not all pigeon’s blood rubies must come from Burma (though most Gübelin/SSEF-certified ones do).
• Commercial “black pigeon blood” is a misleading marketing term — not recognized by labs.

For collectors, understanding pigeon’s blood ruby meaning across labs helps avoid confusion in the gem market.

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Final Thoughts

As Shakespeare said, “A rose by any other name would smell as sweet.” The same is true for rubies. Certificates matter, but color is the soul of a ruby, and personal preference should guide your choice.

At PeonyJewels, we celebrate natural beauty and craftsmanship. Explore our collection of handmade vintage earrings, each piece carrying its own story of artistry and timeless charm.