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Ruby Gemstone - Buying Guide

Red Ruby

With renewed interest in colored gemstones taking center stage lately, we're going to take a closer look at one of the most romantic of all the precious gemstones, the red ruby.

Red Ruby

Ruby.

Said to be one of the rarest of the big three - rubies, sapphires, and emeralds, this crimson rock is July's birthstone, as well as the 15th and 40th anniversary stone.

Named from the Latin "ruber" for red, ruby is a member of the corundum mineral family. When corundum is red, we call it a ruby; when it is any other color, like blue, yellow, and pink, we call it a sapphire.

Selection Of Types Of Rubies

Selection of types of rubies.

Rubies are relatively hard gemstones, ranking 9 on the Mohs' scale, only falling behind the diamond at a perfect 10. That bodes well for wearing rubies every day and not worrying about damaging the stone.

If you are considering buying a ruby to be set in jewellery, then here's our guide of how to buy the best ruby for your money. We will go through the 4Cs in order of their importance:

Color

As with emeralds, the most important factor when evaluating a ruby is its color. The deeper, and more intense the color, the better. Basically we measure color using three criteria: hue, tone, and saturation.

Hue

Hue refers to where the ruby falls in the spectrum of other colors. Each ruby has a primary and secondary color. The primary color is red, and the secondary color is usually orange, purple, or pink. The more the ruby's color is strictly red, the more valuable the ruby.

1.00 carat oval cut ruby with pure red hue

1.00 carat oval cut ruby with pure red hue.

1.00 carat oval cut ruby with purplish hue

1.00 carat oval cut ruby with purplish hue.

Tone

Tone refers to how light or dark the shade of red is, with most good quality rubies falling somewhere between medium and medium dark tone. If the ruby's color is too dark, then it's difficult to make out the color, and if it's too light than the color will be too faint.

Also, if a ruby's tone is too light, it might be considered a pink sapphire - even if the stone has high saturation.

Saturation

Which brings us to our last criterion, saturation. This refers to the ruby's depth of color, or how intense the color is. The more intense the color, the more precious we consider the ruby; a well saturated ruby will most likely be either "strong" or "vivid."

Also, rubies that fluoresce (glow in ultraviolet light) can have even greater saturation, and rutile needles, which are tiny inclusions, may improve the ruby's color by reflecting light from inside the stone. It should go without saying that if the color of a ruby is by far the most important factor, it would be crazy to even consider buying a ruby sight unseen.

For as long as people have cherished the ruddy colors of the ruby, they have been describing its unique color with appellations ranging from "pigeon's blood," and "pomegranate" to "China Rose" and "traffic light red."

Secondary Colors

Some rubies mined from specific locations are known to have certain secondary colors, like rubies from Myanmar that have a slight purple secondary color.

Purple as a secondary color can actually be better because it makes the red appear richer. (Another color tip: set a purplish red ruby in yellow gold like they do in Burma so that the yellow color will neutralize the blue in the purple, thus making the ruby appear even more red.)

Ruby Grading

But unlike diamonds that are graded according to a strict system of letters starting with "D" and going on through alphabet, colored gemstones have no objective grading system. Gemological laboratories use master stones in order to contrast other stones' hues, tones, and saturations.

This is the only way, for example, gemologists can distinguish between pink sapphires and rubies. But it also leaves some room for error, so beware of these murky waters if someone is trying to sell you a ruby that looks a lot more to you like a pink sapphire!

Rather, you will have to use your own judgment about which colors appear vibrant and alive to you, or use the preferred grading system described below. Of course, the better the ruby's color, the higher the price tag will usually be, but be sure to buy only from reputable gemstone jewellers.

Ruby Grading Scale

Rubies are gemstones. Therefore, they can be graded by the preferred grading system for all gemstones: Natural AAA, AA, or A. With this system, rubies can be graded according to different ranks. The categories of this grading system include AAA, AA, A, and B qualities. Below you can see a ruby color chart with the different grading ranks labeled under each stone.

Sapphire Grading Scale

Sapphire grading scale.

Clarity

Clarity refers to the number, size, color, location, and quality of imperfections in the stone, known as inclusions. When gemologists measure the clarity of diamonds, they use 10x magnification to get a super magnified view of the inside of the stone.

With colored gemstones, however, gemologists do not use magnification; rather, they look for what we call "eye-cleanliness," which means that the stone is clean or free of inclusions when viewed by the naked eye. The better the clarity, the more expensive the ruby.

All natural rubies will contain some level of inclusions, also known as rutile needles or "silk." If there are no rutile needles, gemologists will suspect the ruby has been treated, or is synthetic.

Types of inclusions in natural rubies

Various types of inclusions can form within a ruby. Each has a different structure and a different appearance. Different types of inclusions can affect the value of the ruby in different ways. Inclusions can typically be seen with the naked eye, while others can be seen with a 10x microscope.

Silk

Silk

These inclusions look like silk fibers that are commonly found in clusters. They are on the insides of the ruby and look like fine fibers. These inclusions can have litle impact on ruby color and clarity. In mass quantity, they can whiten the ruby and discolor the beautiful red glow and hue. They can affect light performance as well.

These inclusions look like silk fibers that are commonly found in clusters. They are on the insides of the ruby and look like fine fibers. These inclusions can have litle impact on ruby color and clarity. In mass quantity, they can whiten the ruby and discolor the beautiful red glow and hue. They can affect light performance as well.

Crystals

Crystals

The are more solid inclusions that are of various shapes and sizes. They can look like small pinpoints or grains. Because, crystals are typically white or black, their signficantly impact the rubies color, visibility and light performance. All rubies have inclusions, but avoid those with crystal inclusions.

The are more solid inclusions that are of various shapes and sizes. They can look like small pinpoints or grains. Because, crystals are typically white or black, their signficantly impact the rubies color, visibility and light performance. All rubies have inclusions, but avoid those with crystal inclusions.

Needles

Needles

These are long and slender inclusions that are either crystals or narrow tubes. They often look a bit glassy and impact light performance, but less so on color. When larger, they can look like a scratch inside the ruby. Ideally, they are located away from the surface so lower visibility in the gemstone.

These are long and slender inclusions that are either crystals or narrow tubes. They often look a bit glassy and impact light performance, but less so on color. When larger, they can look like a scratch inside the ruby. Ideally, they are located away from the surface so lower visibility in the gemstone.

Crack or Feather

Feather

These are also known as fractures and fissures that can be featherlike in appearance. These inclusions will break the surface of the gemstone and can impact the structural integraty of the ruby. Because rubies are soft, these can be dangerous inclusions when the size is large.

These are also known as fractures and fissures that can be featherlike in appearance. These inclusions will break the surface of the gemstone and can impact the structural integraty of the ruby. Because rubies are soft, these can be dangerous inclusions when the size is large.

Twinning

Twinning

These are also crystals but are structurally two that are growing out of one another. Twinning makes crystals more visible because the size of the overall crystal gets larger. They can impact the visibility of the inclusion and diminish light performance and whiten (or darken) color, depending on the color of the crystal.

These are also crystals but are structurally two that are growing out of one another. Twinning makes crystals more visible because the size of the overall crystal gets larger. They can impact the visibility of the inclusion and diminish light performance and whiten (or darken) color, depending on the color of the crystal.

Fingerprints

Fingerprints

These are quite common in rubies. The inclusions are clustered together and look like small human fingerprints. Because the inclusions are small, they are less likely to impact the quality of the ruby. Only if they fill the ruby up, then you can have issues with the light perfomance and red hue.

These are quite common in rubies. The inclusions are clustered together and look like small human fingerprints. Because the inclusions are small, they are less likely to impact the quality of the ruby. Only if they fill the ruby up, then you can have issues with the light perfomance and red hue.

Cavity

Cavity

These are miniscule holes that extend into the ruby from the surface of the gem. Large cavities are visually unattractive and make a ruby look broken. Additionally the can affect the structural integrity of the ruby, especially when setting the ruby in jewellery.

These are miniscule holes that extend into the ruby from the surface of the gem. Large cavities are visually unattractive and make a ruby look broken. Additionally the can affect the structural integrity of the ruby, especially when setting the ruby in jewellery.

Scratches, Abrasions

Abrasions

These are surface blemishes that look like rough scrapings on the surface of the ruby. Scratches can often be polished away; however, it depends on the size, location and depth of the scratch. If very deep, a lot of weight loss may result from a scratch. Additionally, scratches are typically quite visible because they are surface inclusions.

These are surface blemishes that look like rough scrapings on the surface of the ruby. Scratches can often be polished away; however, it depends on the size, location and depth of the scratch. If very deep, a lot of weight loss may result from a scratch. Additionally, scratches are typically quite visible because they are surface inclusions.

Color Zoning

Color Zoning

All rubies are primarily red but do have other secondary colors. Uneven colors is when the color does not look uniform across the surface of the ruby. Inclusions can often cause color zoning making portions of the ruby look pink. Color zoning is also something impacted by the cutting of the ruby. Cutters try to preserve the red hue and tone to make the color even.

All rubies are primarily red but do have other secondary colors. Uneven colors is when the color does not look uniform across the surface of the ruby. Inclusions can often cause color zoning making portions of the ruby look pink. Color zoning is also something impacted by the cutting of the ruby. Cutters try to preserve the red hue and tone to make the color even.

Select Inclusion Feature

Silk Crystals Needles Feather Twinning Fingerprints Cavity Abrasions Color Zoning

Types of inclusions in natural rubies.

Inclusions That Increase Value

Today most rubies are heat-treated to improve color and clarity, but rubies that are not and have superb quality can fetch big money at market. Interestingly enough, there is one example of inclusions actually increasing the value of the ruby.

This is a rare occurrence called asterism in which three or six-point stars are visible in the stone when viewed under proper lighting. This happens when light is reflected off the rutile needles, thus creating the star effect.

Star Ruby

Star ruby caused by inclusions.

Cut

A ruby's cut refers to how the stone is faceted, its dimensions, and overall symmetry. Unlike with diamonds, rubies are not graded on cut quality. The cut is much less important to consider than the ruby's color and clarity.

But as is the case with most gemstones, the true glow of the ruby is only revealed after a quality cut that maximizes light return and color. There are four factors gem cutters must keep in mind when cutting sapphires and rubies:

  1. Maximize color.

  2. Maximize carat weight.

  3. Minimize inclusions.

  4. Keep in mind what shape the consumer wants, i.e., round, oval, pear and cushion, etc.


Carat

And finally, let's consider the ruby's carat weight. As you probably already guessed, the more carats, the bigger the price tag. Since larger gemstones are rarer than smaller gemstones, you pay more based on the laws of supply and demand.

Colored Gemstone Enhancement

Most reputable jewellers offer consumers only the highest quality, authentic gemstones. Their colored gemstones undergo rigorous internal inspections by trained gemologists to ensure they meet our stringent quality standards.

Due to their rarity and unique visual properties, nearly all colored gemstones sold at reputable jewellers, are enhanced using various techniques. Many of these techniques have been used for centuries. Colored gemstones that have not been enhanced are very rare and command extravagant prices.

While colorless and fancy color diamonds are not enhanced in any way, other than normal cutting and polishing. Black diamond fashion jewellery contains natural diamonds that have been treated to create the unique black color.

Ruby clarity enhancing treatments

Often times, treatments are used to enhance or improve the clarity of the ruby. While some are common, and permanent, others are not as desirable. It is important to understand the differences between all types of treatments.

Ruby Properties

Mineral Class Corundum
Chemical Name Aluminium oxide
Chemical Formula AI203
Crystal System Trigonal
Colors Red
Hardness 9 on the Mohs scale
Refractive Index 1.76 - 1.78
Specific Gravity 4.0 - 4.1
Transparency Transparent to opaque
Birefringence -0.008
Lustre Vitreous
Cleavage None
Streak Colorless
Fluorescence Strong - carmine red

Ruby properties.

New & Future Technologies

Techniques for enhancing colored gemstones, either detectable or otherwise, are continually being developed. These may be difficult, or in rare cases, impossible to detect, even for the most sophisticated laboratory. Reputable jewellers will continue to work with industry groups and gemological experts who are committed to the identification and disclosure of new and future techniques in order to maintain our stringent quality standards.

Basic Gemstone Care

While gemstones are durable, they require varying levels of care. For example, some gemstones are especially vulnerable to household chemicals and temperature changes. Cleaning gemstones presents special challenges. While many gemstones should be cared for by following our basic care guidelines below:

Final Thoughts

You should also be aware that there are usually price jumps when you hit 1.00 carat, as well as 3.00 and 5.00 carats. If you want to buy a 1.00 carat ruby, consider going for a 0.90 ct. instead since most likely you will not notice the difference in size once set, but you will notice the savings in your wallet!