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.
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.
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:
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 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 purplish hue.
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.
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."
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.)
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.
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:
Natural AAA: This grade represents just 1% of all natural gemstones. Any rubies in this category are extremely rare and expensive.
Natural AA: This grade accounts for 10% of all natural gemstones that are available in the world. Any rubies in this grade are typically considered high quality, and this is the best grade to use for fine jewellery making.
Natural A: This grade forms the top 20% of natural gemstones. It's not as amazing as the AA grade, but it's still considered to be great. Fine jewellery is also made using this grade.
Natural B: This category accounts for over 50% of natural gemstones.
Sapphire grading scale.
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.
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
Crystals
Needles
Crack or Feather
Twinning
Fingerprints
Cavity
Scratches, Abrasions
Color Zoning
Select Inclusion Feature
Types of inclusions in natural rubies.
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 caused by inclusions.
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:
Maximize color.
Maximize carat weight.
Minimize inclusions.
Keep in mind what shape the consumer wants, i.e., round, oval, pear and cushion, etc.
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.
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 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.
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:
Heated Rubies: The most commonly used treatment is heat. The majority of rubies are heat treated to remove rutile inclusions and improve the color tone and saturation. This treatment is permanent and mimics the natural processes that rubies undergo while forming. It is a common treatment that enhances the value and the appearance of natural rubies. While undergoing this treatment, the ruby is placed under a high temperature of 1800 degrees. The heat dissolves the rutile inclusions and improve the color, transparency and clarity of the ruby. The resulting ruby is as natural, durable as the original ruby before treatment. No other additives or materials are used to alter the ruby is any fashion.
Flux Healed Rubies: Often times, rubies are coated in a material prior to heating. This creates a barrier and prevents the rubies from sticking together during the heating process. At times, this flux materials can melt and enter the cracks and fissures that are in a ruby. This can improve the clarity of the ruby by filling in the cracks. However, the treatment introduces foreign substances into the ruby and therefore decreases it's value.
Beryllium Diffused Rubies: In this treatment, beryllium is added to the ruby as it is being heated. This treatment enhances the color of the ruby producing a more vibrant red color. The beryllium permeates the crystal lattice of the gemstone.
Glass Filled Rubies: This is a newer treatment that is used to enhance lower grade rubies. The ruby is bleached and treated with the addition of a liquified glass. The glass penetrates the ruby and improves the clarity of the ruby. The visibility of the cracks is lessened. However, this treatment is the least desirable as it is not stable with temperature changes or when the ruby is subjected to ultrasonic cleaners.
| 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.
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 stringent quality standards.
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:
Cleaning: After removing your gemstone jewellery, clean it by following the directions on a non-abrasive jewellery cleaner. Make sure that the jewellery cleaner specifies that it is safe to use with your gemstone. Use a soft cloth to remove any remaining dirt or other residue.
Storing: Store your gemstone jewellery in a lined case or a soft cloth, so the gems do not touch each other or parts of other jewellery. Gemstones are harder than gold, silver, or platinum and can scratch the surfaces of your other fine jewellery if they are not kept separate.
Wear: While it's true that gemstones such as ruby and sapphire are second only to diamond on the hardness scale, it is not a measurement of their indestructibility. It means that these gemstones are able to resist scratching almost as well as a diamond. Abrasive surfaces, harsh chemicals, and sharp blows can damage even the hardest gem. Your gemstone jewellery should be the last thing you put on when getting dressed and the first thing you take off at the end of the night. Store your gemstones carefully and they will be enjoyed for generations.
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!
