All About Rubies: Fine Jewelry Grading, Origin & July Birthstone Facts

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The Rare Red Gemstone: Science, Grading & Everything Else About Rubies & Their Value

Rubies rank among the top four (4) most valuable gemstones, the other three being: emerald, sapphire, and diamond. This is due not only to their striking color, but their rarity. A jewel of kings, this gemstone has inspired tales of passion and fortune. Today it is a colorful alternative to the traditional diamond engagement ring and makes lovely fine jewelry. If you are in the market to purchase rubies, here is what you need to know before you buy.

Rubies are the July birthstone and make excellent gifts!

Science Class Is In Session: What Is A Ruby & How Is It Made?

These colored gemstones are truly science experiments of the earth, true intrigues for chemists. Like sapphires, rubies are a corundum, which means that their chemical make up is aluminum oxide. However, by a twist of chemistry, rubies get their red color when chromium replaces 1% of the aluminum atoms. Add ferric iron to the equation and you have rare orange & pink rubies.


If there is any silica or plain old iron present, a ruby cannot form. As any high school science teacher can tell you, these two elements are extremely abundant in the earth’s crust. On top of that, corundum is a rare element. Since the conditions of ruby formation are so specific, rubies themselves cannot be anything but scarce. This is why they will fetch higher prices than diamonds, which are much more common.

Ruby Grading: Color, Clarity, Carat & Cut

Rubies with grading AAA to B from left to right.

Like many colored gemstones, a ruby is given one of the following grades by a jewelry & gemstone appraisal expert based on its color, clarity and cut:

AAA: These are the most rare and valuable rubies on the market. In fact, this grade only makes up 1% of all gemstones in general.

AA: Anyone shopping for fine jewelry with rubies should aspire to find gemstones with this grade. Although they make up 10% of the market, they are the best choice for fine jewelry, both in beauty and durability.

A: Although this grade is not as impressive as its AA counterpart, rubies in this category are also acceptable for fine jewelry. They are also more common, making up 20% of the ruby market.

B: This is the grade given to well over 50% of the colored gemstones on the market. However, with this low grade, the gem is lacking in radiance and can even have durability issues if there are too many inclusions.

Ruby Color Grading: Why Color Is The Most Important Aspect & What Is The Best Ruby Color

18k White Gold Three Row Ruby and Diamond Band

As with many other precious gemstones, color is the most important factor when grading rubies. The color grading depends on three (3) factors:

1. Hue: Rubies can range in color spectrum from orange—red—purple in hue. A specimen with an ideal color will be a pure red hue. As the color moves more orange or purple, the value of the ruby goes down.

2. Saturation: This is what gives a ruby it its intensity.

Saturation ranges from vivid—strong—fair—medium—weak. Vivid is the most prized in on the spectrum.

3. Tone: How much color does the ruby have? This scale ranges from very dark—dark—medium—light—very light. Medium is the best grade in tone to look for.

The best color grade for a ruby is: A vividly saturated red hue with a medium tone.

Ruby Clarity Grading: It’s The Flaws That Matter!

With diamonds, clarity is a huge factor, but with rubies imperfections play a more interesting role. Since rubies are so rare, imperfections (aka: rutile needles or silk) are like Persian rugs: all the genuine ones have a flaw. If a ruby is lacking rutile needles, then buyer beware! It’s likely lab created.

While minor inclusions mark a ruby’s authenticity, too many can compromise both the beauty and durability of the stone, causing the grade to go down.

Clarity grading for rubies is the same as other colored gemstones. See the full breakdown on the Gemstone Buying Guide.\

Ruby Carat Grading: Size Isn’t Everything, But It Does Come With A Price Tag

As with diamonds and other colored gemstones, a ruby’s value will increase with carat size. Larger stones are more rare, so their price tag will jump with it.

Ruby Cut Grading: Why Some Styles Are More Common Than Others

Lisette 18k Ruby and Diamond Ring

Due to the typical crystal structure of rubies, they are commonly cut in oval and cushion styles for fine jewelry. These are the most flattering for the stone’s brilliance. Other cuts are typically seen only with larger rubies. Still, the shape of the cut means little if the skill of the jeweler is poor. An expert will cut the gemstone so precisely in accordance with its crystal structure that the ruby’s maximum beauty is achieved.

A lesser cut on a quality stone will not have the same effect, causing the grade to drop.

Fun Fact & Superstitions About Rubies From Around The World

England’s Imperial State Crown with the Black Prince’s Ruby.

1. Ruby gets its name from the Latin word ruber for red.

2. Ruby is the July birthstone.

3. Many ruby deposits are where the land meets the Himalayan Mountains. The right elements, plus pressure from tectonic plate collision was the perfect recipe for ruby formation.

4. In the Hindu religion, the ruby is the most prized gemstone.

5. Rubies began to form over 50 million year ago.

6. The Black Prince’s Ruby is not a ruby…it’s a spinel!

7. It was believed that wearing a ruby on the left-side by the heart acted as a protective talisman.

8. The ancient Burmese believed rubies to be the stone of soldiers and would put it into the skin to make them

invincible in battle. (We don’t recommend this…at all.)

9. There is a superstition that wearing a ruby will bring you wealth.

Rubies and mankind have a long history together and the tradition continues today. Whether you are looking for a personalized gift like fine birthstone jewelry or a unique engagement ring, rubies are a striking choice. Come into one of Hamilton’s locations to see how they dazzle in person, or chat with us online to learn about your options. Our fine jewelry and gem experts have over 100 years of experience. Trust us to help you make the most dazzling purchase!