Ruby

saf-ahyuh r
July Birthstone

The sole birthstone for July, ruby is the brightest and boldest of all birthstones. Called ratnaraj, meaning the "King of Gems" by ancient Hindus, ruby's association with the blood of life has earned it powerful praise and high esteem since antiquity. Ruby is mentioned at least four times in the Bible, always in reference to beauty and wisdom. Its passionate red color makes ruby an ideal choice for a romantic gift that comes with a rich legacy.

Ruby Polished
Ruby Classification
Common Name Ruby
Species Corundum
Ruby Optical Properties
Transparency Transparent - Opaque
Dispersion Strength: Moderate Fire Value: 0.018
Refractive Index 1.762-1.770
Tolerance:(+0.009/-0.005)
Birefringence 0.008-0.01
Optic Character Uniaxial
Optic Sign Negative
Polariscope Reaction Doubly Refractive (DR)
Fluorescence SWUV: Weak to strong red
LWUV: Weak to moderate red
CCF Reaction Red glow
Pleochroism Dichroic, moderate to strong orangy red and purplish red
Ruby Characteristic Physical Properties
Hardness 9
Streak White
Specific Gravity 3.950-4.100 Typical:4.000
Toughness Excellent
Inclusions This stone has type II clarity. Sometimes rubies have silk, rutile, boehmite, apatite, calcite or zircon crystals, fingerprint and negative crystal inclusions. Some stones show hexagonal growth and color zoning. Untreated stones will usually have inclusions intact. Heat treated stones will have fracture halos, discoid fractures or snowballs around crystal inclusions (untreated stones from magmatic areas might also show these characteristics). Silk will be broken and might show sintered areas especially around the girdle.
Luster Bright Vitreous
Stability Excellent
Fracture Conchoidal, Uneven
Cleavage None
Ruby Chemistry & Crystallography
Chemical Name aluminum oxide
Chemical Formula Al2O3
Crystal System Trigonal
Chemistry Classification Oxide

Ruby Colors

  • Red Ruby Red
  • Red Ruby Red
  • Red Ruby Red

Ruby Spectra

Ruby Spectra
RUBY - BURMA UNTREATED (ε ray)

Broad central absorption has narrowed. The two lines at 668nm. and 659nm. are seen as fluorescent lines. Fluorescence in fine specimens can be as strong as that seen in lab created rubies.

Ruby Spectra
RUBY - VERNEUIL lab created. (Unpolarized

Color due to chromium. Controlled supply of chromium oxide in the production of modern lab created ruby can result in a more intense, slightly purplish red stone. The resulting spectrum shows an intense dark absorption band centered at 550nm. together with the usual features of the lines in the blue and the fluorescing doublet in the deep red. The violet is totally absorbed

Ruby Spectra
RUBY - VERNEUIL Lab Created (Unpolarized

Color due to chromium. The absorption spectra is essentially the same for that of natural ruby. Fine lines in blue plus lines in the red. Near the left side of the red, the thick line may appear as double. The line may even glow as an emission line, particularly if the stone is being viewed in reflected light

Ruby Spectra
RUBY - VERNEUIL lab created. (Fluorescence spectrum

An intense light source placed close to the stone and scattered from within it, can enter the spectroscope slit indirectly. In this way a subdued spectrum is seen in which any fluorescence lines stand out against a dark background. In the modern chromium rich, iron free, lab created ruby a spectacular group of fluorescing lines may be seen, dominated by the intense doublet at 693/693nm

Ruby Spectra
RUBY - VERNEUIL Lab created (Fluorescence spectrum

When the lighting is suitably adjusted the doublet at 693/694nm. can be seen as a dark absorption line. If only the o-ray ray is observed this doublet will be seen at its strongest together with finer lines at 668nm. and 659nm. The Broad absorption now extends from 610nm. to 495nm. leaving a narrower window in which the absorption lines at 468nm. and 475/476nm. appear more intense, after which total absorption follows

Ruby Spectra
RUBY - VERNEUIL lab created. (ω ray)

This gem usually shows an intense dark absorption band centered at 550nm. together with the usual features of the lines in the blue and the fluorescing doublet in the deep red. The violet is totally absorbed.

Ruby Spectra
RUBY - VERNEUIL Lab Created (ω ray)

Color due to chromium. The absorption spectra is essentially the same for that of natural ruby. Fine lines in blue plus lines in the red. Near the left side of the red, the thick line may appear as double. The line may even glow as an emission line, particularly if the stone is being viewed in reflected light. The stronger and more purplish pink color of the o-ray causes the central absorption band to broaden. The doublet in the red is seen to be fluorescing fairly strongly which is characteristic of the o-ray. The lines in the blue are prominent and the violet totally absorbed

Ruby Spectra
RUBY - VERNEUIL lab created. (ε ray)

This gem usually shows an intense dark absorption band centered at 550nm. together with the usual features of the lines in the blue and the fluorescing doublet in the deep red. The violet is totally absorbed. As we rotate the polarizing filter and isolate the e-ray variations occur in the spectrum. The doublet in the red is less intense and the fine line in the red at 595nm. is present but the one at 668nm. seen in the o-ray is now absent. The main absorption band has become narrower and the blue area has widened considerably to show the lines clearly before total absorption takes over

Ruby Spectra
RUBY - VERNEUIL Lab Created (ε ray)

The absorption spectra is essentially the same for that of natural ruby. Fine lines in blue plus lines in the red. Near the left side of the red, the thick line may appear as double. The line may even glow as an emission line, particularly if the stone is being viewed in reflected light. In this instance the color produced by the e-ray is more of an orange pink, as a result of which the intensity and width of the central absorption band is considerably diminished. This allows more transmission of orange and green light in this direction. The fluorescence of the doublet in the red is weaker but the lines in the blue are still prominent before total absorption takes over in the violet.

Ruby Spectra
RUBY - THAI UNTREATED (Unpolarized)

Color due to chromium. The spectrum of this rather dark purplish red ruby shows the typical broad absorption band in the green area and the fluorescing doublet at 694/693nm. in the red associated with chromium. However, due to the high iron content the fluorescing doublet is weak and the lines in the blue rather vague

Ruby Spectra
RUBY - THAI UNTREATED (Fluorescence spectrum)

The iron content has weakened the fluorescence considerably and any attempt to capture this in scattered light is poor

Ruby Spectra
RUBY - THAI UNTREATED (ω ray

The spectrum typically shows a broad absorption band in the green area and the fluorescing doublet at 694/693nm. in the red associated with chromium. When the o-ray is polarized via the pavilion facets the central absorption band broadens and the doublet in the red fluoresces more strongly. However, absorption in the deep blue-violet area increases, making it more difficult to resolve the lines in the narrow blue window. This could be because of further absorption in this area due to the iron content.

Ruby Spectra
RUBY - THAI UNTREATED (ε ray)

The spectrum typical shows a broad absorption band in the green area and the fluorescing doublet at 694/693nm. in the red associated with chromium. However, due to the high iron content the fluorescing doublet is weak and the lines in the blue rather vague. The most noticeable difference in the e-ray is the considerably narrower center absorption band. The fluorescing doublet is again much weaker and although transmission in the green-blue area has increased, the narrow lines are still difficult to see due to the greater absorption in the deep blue.

Ruby Spectra
RUBY - KASHAN Lab Created (Unpolarized)

The typical chromium spectrum of a broad band centered at 550nm.in the green and the lines in the blue at 476/475nm and 468nm. are present. However, the doublet in the red at 694/693nm. is constantly seen as an emission line, rather than appearing as dark absorption lines

Ruby Spectra
RUBY - KASHAN Lab Created (Fluorescence spectrum)

In scattered lighting conditions the doublet in the deep red is seen as a strongly fluorescing emission line, and occasionally the two lines at 668nm. And 659nm. may also be seen to fluoresce, even if they are not easily detected as absorption lines in transmitted light

Ruby Spectra
RUBY - KASHAN Lab Created (ω ray)

The typical chromium spectrum of a broad band centered at 550nm.in the green and the lines in the blue at 476/475nm and 468nm. are present. However, the doublet in the red at 694/693nm. is constantly seen as an emission line, rather than appearing as dark absorption lines. A slight increase in the width of the central absorption band. The doublet in the red continues to fluoresce and the lines in the blue are still present.

Ruby Spectra
RUBY - KASHAN Lab Created (ε ray)

The typical chromium spectrum of a broad band centered at 550nm.in the green and the lines in the blue at 476/475nm and 468nm. are present. However, the doublet in the red at 694/693nm. is constantly seen as an emission line, rather than appearing as dark absorption lines. Rotating the polarizing filter 90 degrees produces a narrower and less intense absorption in the green area which allows more transmission of orange light. The other lines are also weaker.

Ruby Spectra
RUBY - BURMA UNTREATED (Unpolarized)

Color due to Chromium Fluorescence of the strong doublet at 694/693nm. A broad absorption band centered at 550nm. Violet is absorbed and lines are seen in the remaining blue window at 476/475nm. and 468nm. Other fine lines normally seen in the red have been masked by the intense transmission in this area.

Ruby Spectra
RUBY - BURMA UNTREATED (Fluorescence spectrum)

Light scattering can be induced by manipulation of the light source to an extent that mainly the red area of the spectrum is transmitted. As a result, any fluorescence is intensified and becomes more visible. In this way the two lines at 668nm. and 659nm. are seen as fluorescent lines, together with the intense doublet at 694/693nm.

Ruby Spectra
RUBY - BURMA UNTREATED (ω ray)

Color due to chromium. Strong fluorescence of the strong doublet at 694/693nm. A slightly broader absorption band centered at 550nm. Violet is absorbed and lines are seen in the remaining blue window at 476/475nm. and 468nm. Other fine lines normally seen in the red have been masked by the intense transmission in this area.

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Alternate Names

Mahaleo Ruby

Countries of Origin

Tanzania, United Republic Of; Myanmar; Afghanistan; Viet Nam; Czechia; Guinea; Madagascar; Thailand; Sweden; Mozambique; Pakistan; Morocco; Unknown; China; Russian Federation (the); Brazil; Nigeria; Argentina; United States of America (the); Sri Lanka; Zambia; Kenya; Switzerland; India; Norway; Namibia; South Africa; Ethiopia; Indonesia

History

Rubies. We desire them. Their rich reds are powerful, seductive, and inflaming. Ruby has been a treasure for centuries - the ancient Hindus named it the King of Gems. In fact, the Sanskrit word for ruby is ratnaraj, which means, "the King of Gems." Ruby is considered the gemstone of passion and of lovers; it's the quintessential symbol for red. Fine rubies are among the most costly and valuable gems of the corundum family, which includes sapphires in all colors (except red). Ruby is a 9 on the scale of hardness, so it's a fabulous choice for a wear-every-day, signature gemstone. It's red color works with white, rose, or yellow metals, which means you have plenty of options in jewelry. July babies, this is your birthstone. But move over - there are plenty of us who wear rubies for the sheer beauty of them!

Care

Untreated and heated rubies just need normal care. Avoid recutting or chipping coated or surface diffused stones. Avoid common household chemicals, steam cleaners, ultrasonic cleaners and a jeweler’s torch with lead glass filled, dyed or oiled/resin filled stones.

Related Videos

More About Ruby

Rubies rank among the four gemstones once called precious: diamond, emerald, ruby and sapphire. Their red color has put them in the forefront of folklore for centuries. The early Burmese thought ruby would impart invulnerability to the wearer, which made it a must in battle. In the middle ages, it was believed that ruby had an inner fire that could not be extinguished. And in the 16th century it was written that ruby had magical powers and could, "preserve health, remove evil thoughts, reconcile disputes and control amorous desires"... among other things. Choose your ruby, get it home, wear it and enjoy it. You'll see why we at JTV® revere it.

Sisk Gemology Reference

Showcasing 200 gemstones in over 1,000 pages and accompanied by more than 2,000 photos, The Sisk Gemology Reference is a must-have in every collector’s library. Each comprehensive, three-volume set features state-of-the-art photography, detailed illustrations, and scientifically precise descriptions to create an entrancing experience for gemstone amateurs and afficionados alike.

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Creation Method

Lab Created Czochralski

Synthetic ruby can be created in many ways, one of which is called the Czochralski method. During this process, the various elements that make up ruby are melted in a platinum crucible. A small gem crystal (called a seed) attached to a rod is then dipped into the melt and slowly pulled away as the crystal grows around the seed. For this reason, the Czochralski method is also known as crystal pulling. Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Created Czochralski Ruby
Lab Created Czochralski Classification
Common Name Lab Created Czochralski
Lab Created Czochralski Optical Properties
CCF Reaction red
Lab Created Czochralski Characteristic Physical properties
Specific Gravity 3.950
Toughness Excellent
Inclusions Stones are almost always inclusion free. If internal characteristics are present they are gas bubbles, curved striae that is hard to see and smoke-like swirling veil-like inclusions.
Stability Excellent

Lab Created Hydrothermal

Hydrothermally grown synthetic rubies crystallize slowly out of a solution (a mix of water and dissolved elements) that has been exposed to heat and pressure similar to the conditions on Earth under which the natural gem mineral grows. Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Created Hydrothermal Ruby
Lab Created Hydrothermal Classification
Common Name Lab Created Hydrothermal
Lab Created Hydrothermal Optical Properties
CCF Reaction red
Lab Created Hydrothermal Characteristic Physical properties
Specific Gravity 3.950
Toughness Excellent
Inclusions Look for chevron, wavy, zig-zag or mosaic growth patterns in hydrothermal synthetic ruby because stones might show growth zoning similar to natural ruby. Fingerprint like inclusions with 2-phase and 3-phase inclusions can be seen in stones. Sometimes flake like copper inclusions are visible in reflected light.
Stability Excellent

Lab Created Flux

One method of creating synthetic ruby is called flux growth. During the flux growth process, flux, a substance that reduces the melting point of surrounding material, is combined, in a metal-lined crucible, with the elements that make up a specific gem mineral. The crucible is heated until its contents are liquid and then it is allowed to cool very slowly. As cooling continues, the gem mineral crystallizes from the solution. Flux grown synthetic gems can take up to a year to grow to a facetable size, but the exceptional clarity of these gems is well worth the wait! Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Created Flux Ruby
Lab Created Flux Classification
Common Name Lab Created Flux
Lab Created Flux Optical Properties
CCF Reaction red
Lab Created Flux Characteristic Physical properties
Specific Gravity 3.950
Toughness Excellent
Inclusions Platinum platelets from the crucible that appear metallic in reflected light but appear dark when stone is lit from behind. Flux is often white, brownish, yellow or orange but can be colorless. Flux inclusions can appear like natural fingerprint inclusions, wispy veils, comet tails, coarse globules of flux that can have a myriad of appearances from drippy, tubular or rod like or icicle looking, to clouds and minute particles, Stone might display angular growth zoning similar to natural.
Stability Very Good

Lab Created Flame Fusion

The flame fusion process for creating gems, also called the Verneuil process, is the most affordable and common synthesis method for producing corundum (ruby and sapphire) and spinel. Powdered chemicals (the building blocks of the gem) are dropped through a high-temperature flame. The molten powder repeatedly falls from the flame onto a rotating pedestal, creating a synthetic crystal, called a boule, which can later be faceted into a gemstone. Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Created Flame Fusion Ruby
Lab Created Flame Fusion Classification
Common Name Lab Created Flame Fusion
Lab Created Flame Fusion Optical Properties
CCF Reaction red
Lab Created Flame Fusion Characteristic Physical properties
Specific Gravity 3.950
Toughness Excellent
Inclusions Stones may display face up pleochroism, curved striae that crosses facet junctions and strings of gas bubbles that might be mistaken for needles. It might be possible to see Plato lines or twinning planes under magnification and immersion with polarized light. Sometimes heated with borax to created fingerprint like inclusions to mask curved striae.
Stability Excellent

Lab Created Floating Zone

One method of creating synthetic ruby is called floating zone. In this method of gem synthesis, originally developed by engineers to create super pure silicon, a sintered rod of powdered material, comprised of elements necessary for the gem to grow, is heated with infrared radiation in a vacuum while the ends of the rod are rotated in opposite directions. Since all impurities including air are removed during crystallization, very clean crystals can form.

Lab Created Floating Zone Ruby
Lab Created Floating Zone Classification
Common Name Lab Created Floating Zone
Lab Created Floating Zone Optical Properties
CCF Reaction red
Lab Created Floating Zone Characteristic Physical properties
Specific Gravity 3.950
Toughness Excellent
Inclusions Stones are almost always inclusion free. If internal characteristics are present they are gas bubbles that are not perfectly round and swirls of color.
Stability Excellent

Optical Phenomena

Star

Star rubies will have silk or sets of parallel rutile needles that produce a 6-ray star, hexagonal growth lines, color zoning and mineral inclusions. Weak and less well-formed stars along with weaker body color is typical of natural stones. In natural stones at least one ray of the start will be perpendicular to the hexagonal growth zones.

Star Ruby
Star Classification
Common Name Star
Star Characteristic Physical properties
Specific Gravity 3.950
Toughness Good
Stability Good

Cat's Eye

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case ruby. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light through the crystal, scattering and reflecting light back to the viewer as a thin line.

Cat's Eye Ruby
Cat's Eye Classification
Common Name Cat's Eye
Cat's Eye Characteristic Physical properties
Specific Gravity 3.950
Toughness Good
Inclusions Cat's-eye rubies will have silk or sets of parallel rutile needles, hexagonal growth lines, color zoning, liquid, negative and mineral inclusions. Some stone might show twinning.
Stability Good

Lab Created Flame Fusion Star

Synthetic star ruby exhibits the optical phenomenon called asterism, a star-like pattern created on the surface of a gemstone when light encounters parallel fibrous, or needle-like, inclusions within its crystal structure. Light that strikes the inclusions within the gem reflects off of the inclusions, creating a narrow band of light. When two or more intersecting bands appear, a star pattern is formed. The flame fusion process for creating gems, also called the Verneuil process, is the most affordable and common synthesis method for producing corundum (ruby and sapphire) and spinel. Powdered chemicals (the building blocks of the gem) are dropped through a high-temperature flame. The molten powder repeatedly falls from the flame onto a rotating pedestal, creating a synthetic crystal, called a boule, which can later be faceted into a gemstone. Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Created Flame Fusion Star Ruby
Lab Created Flame Fusion Star Classification
Common Name Lab Created Flame Fusion Star
Lab Created Flame Fusion Star Characteristic Physical properties
Specific Gravity 3.950
Toughness Good
Inclusions Flame fusion stones might display curved growth and a unusually display a centered and well defined 6-rayed star. The curved growth is especially visible on the flat base of the stone. The stones might have gas bubbles and minute rutile needles that make up the star will confined to the surface of the stones.
Stability Excellent

Lab Created Czochralski Star

Synthetic star ruby exhibits the optical phenomenon called asterism, a star-like pattern created on the surface of a gemstone when light encounters parallel fibrous, or needle-like, inclusions within its crystal structure. Light that strikes the inclusions within the gem reflects off of the inclusions, creating a narrow band of light. When two or more intersecting bands appear, a star pattern is formed. The Czochralski process of gem synthesis involves the melting of various elements in a platinum crucible. A small gem crystal (called a seed) attached to a rod is then dipped into the melt and slowly pulled away as the crystal grows around the seed. For this reason, the Czochralski method is also known as crystal pulling. Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Created Czochralski Star Ruby
Lab Created Czochralski Star Classification
Common Name Lab Created Czochralski Star
Lab Created Czochralski Star Characteristic Physical properties
Specific Gravity 3.950
Toughness Good
Inclusions Pulled synthetic star ruby will have extremely fine needles that produce a slightly wavy natural looking 6-rayed star. The stones typically show low-relief curved striae or wavy growth. Sometimes bluish white smoke-like swirls and small round or distorted blackish gas bubbles are seen in stones.
Stability Excellent

Material Combination

Lab Created Ruby Overgrowth on Natural Corundum Seed

Synthetic ruby overgrowth corundum has a layer of lab created ruby grown on a colorless corundum.

Lab Created Ruby Overgrowth on Natural Corundum Seed Ruby
Lab Created Ruby Overgrowth on Natural Corundum Seed Classification
Common Name Lab Created Ruby Overgrowth on Natural Corundum Seed
Lab Created Ruby Overgrowth on Natural Corundum Seed Characteristic Physical properties
Specific Gravity 3.950
Toughness Good
Inclusions Color on these stones is strong table up but patchy on the pavilion when viewed on a white piece of paper. The stones have wavy growth that can appear step like or crystalline. One might be able to see facet junctions of the original stone underneath the overgrowth layer that do not match the facets of the outer layer. Stones will probably show uneven color due to removal or the overgrowth layer. They have a mottled or roiled texture when stone is viewed with immersion.
Stability Good

Enhancement

Flux Healed

Flux healed rubies have been heated in the presence of a flux material like borax. The flux will penetrate fissures in the stone and will act like a catalyst to heal the fracture in the stone. The flux will help melt the surrounding ruby to fill in the fissure and improve the clarity in the stone.

Flux Healed Ruby
Flux Healed Classification
Common Name Flux Healed
Flux Healed Optical Properties
CCF Reaction red
Flux Healed Characteristic Physical properties
Specific Gravity 3.950
Toughness Excellent
Inclusions Flux like residue in fissure. It will not be as thick as flux grown rubies. It might have small air bubbles in fissure.
Stability Excellent

Lead Glass Filled

Lead glass filled rubies have been filled through a process similar to "infilling" using lead glass. Performed at lower temperatures, this is a less durable treatment and should be treated gently, avoiding household and professional chemicals. This treatment improves clarity, color, durability, and may add weight through the filling of voids and fissures.

Lead Glass Filled Ruby
Lead Glass Filled Classification
Common Name Lead Glass Filled
Lead Glass Filled Characteristic Physical properties
Specific Gravity 3.950
Toughness Poor
Inclusions Lead glass filled rubies will show gas bubble sand color concentrations in fissures. Blue flash colors from the lead glass filling might be seen when viewing stone in dark field lighting.
Stability Poor
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.