Ruby Buying Guide


“3.03ct Oval Ruby,” Winza, Tanzania, purplish red. ©All That Glitters. Used with permission.
“3.03ct Oval Ruby,” Winza, Tanzania, purplish red. © All That Glitters. Used with permission.

Ruby is one of the most sought after (and expensive) gemstones on the market. This gem’s exceptional hardness makes it very resistant to scratching. This quality makes it possible to wear ruby jewelry every day for any occasion. The highly-prized deep, red color of the finest rubies is popularly associated with love and passion. A ruby can make a strong symbolic statement. Inclusions, which would detract from the allure of other stones, can bring a unique character to a ruby and, in rare cases, a beautiful “star stone” effect.

However, because gem-quality natural rubies are rare and the demand so great, synthetics and imitations are common. Rubies are also subjected to more treatments and enhancements than most other gems. Before you embark on a ruby buying adventure, learn how to evaluate a ruby’s quality and avoid potential pitfalls.

Ruby Buying And The 4 Cs

Color and carat or size have the greatest effect on a ruby’s value. Rubies from Myanmar (formerly Burma) possess the highly coveted “pigeon blood red” color. (In October 2016, the US lifted its embargo on Myanmar rubies. Previously, only Myanmar rubies imported prior to 2003 were available for sale in the US).

The International Gem Society (IGS) ruby value listing has price guidelines for rubies from various sources with different color and clarity grades, sizes, and cut styles.

Color

In the GIA color grading system, color consists of three qualities: hue, tone, and saturation. The basic hues are red, orange, yellow, green, blue, violet, and purple. Tone refers to a color’s relative lightness, from colorless (0) to black (10). Saturation refers to a color’s intensity, from grayish or brownish (1) to vivid (6). The dominant hue is capitalized. Other hues present are not capitalized and may be further described as “sl” for slightly and “st” for strongly.

The color of a top ruby consists of a hue of red, R, a deep tone, 6, and a vivid saturation, 6. This color grade is noted as R 6/6. Only the corundum family of gems, rubies and sapphires, reaches vivid levels of saturation.

Very good color rubies range from R 5/6, R 7/5, slpR 5/6, slpR 6/6, slpR 7/5, to stpR 6/6. Good color rubies range from R 6/5, slpR 6/5, to stpR 5/6.

Clarity

Clarity refers to a gem’s transparency and anything that can impact how it transmits light. All corundum gems, including ruby, are Type II gems in terms of clarity. That means rubies usually contain inclusions. These are fractures and other materials, such as liquids, gasses, and even crystals of other minerals, within their structure. For example, some rubies contain inclusions of crystal needles of the mineral rutile. These crystals within a ruby may create a stunning star effect.

Top tier values for rubies of the same color grade go to stones that are clarity graded VVS (very very small inclusions), or what gemologists refer to as “loupe clean.”  This means that even when examined with a 10x loupe, no inclusions can be detected. These gems are of course also eye clean.  Loupe clean rubies require microscopic examination in order to identify the nature and character of any inclusions.  Since loupe clean rubies are so rare, especially in larger sizes, a buyer should be extremely cautious and seek the counsel of a highly reputed laboratory to verify natural origin and lack of treatments before purchasing.  In my experience, there are no “deals” to be had in fine ruby – if it seems to good to be true, it almost certainly is.  Finding a ruby of this quality, in any size over one carat, irrespective of price, is a challenge.

The second tier of value for rubies of the same color grade are stones that are clarity graded VS (very small inclusions) but still “eye clean” to SI (small inclusions) which may very well not be “eye clean.” In both instances, inclusions are numerous and/or large under a 10x loupe or are eye visible.  The prominence of inclusions visible to the naked eye is the primary driver of value within this tier.  If inclusions are prominently visible to the naked eye from any viewing distance, the value is impacted downward dramatically.  Most all commercially available “gem quality” rubies fall somewhere within this second tier.

The third tier of value for rubies of the same color grade are stones that are clarity graded SI to I (included), or clearly “not eye clean.” These eye visible inclusions may have a moderate effect on durability, and/or may be so prominent that the stone isn’t suitable for use in jewelry.  These rubies are plentiful.

"Inclusions in a Myanmar or Burmese ruby" by Donald Clark.
“Inclusions in a Myanmar or Burmese Ruby” by Donald Clark.

Cut

Most rubies are “native cut” in their country of origin. As a result, high-quality rough rarely makes it to custom gem cutters. Native cut stones can be custom recut, but at a loss of size. However, custom cutting or recutting rubies can command more value per carat. Although cutting usually has the least impact of the 4 Cs on the value of colored gemstones, the quality and choice of cut does affect the value of a ruby. Cuts that maximize light return, such as brilliant cuts, or those that enhance color, such as step cuts, are recommended. Emerald cuts add the most to a ruby’s value, followed closely by round, pear, and marquis cuts. Oval and cushion cuts are common for rubies.

A cabochon cut can make a ruby with the right arrangement of rutile crystal inclusions display a lovely asterism or “star stone” effect. Cabochons can also be used for rubies with inclusions that would be considered too unsightly for faceting.

Carat

Gem-quality rubies larger than 1 carat are very rare, and larger than 2 carats rarer still. The price of rubies per carat shoots up dramatically at those sizes.

Ruby Buying: Jewelry Considerations

If money is no object and only the largest, cleanest, most vivid rubies will do, skip ahead to the Caveats section.

It doesn’t take a large ruby to make an impression. This stone has its reputation and rarity working for it. A masterfully custom-cut, brilliant red stone will attract attention no matter the carat weight.

“Ruby,” held by beeswax, by Mauro Cateb is licensed under CC By 2.0
“Ruby,” held by beeswax, by Mauro Cateb is licensed under CC By 2.0

Although red and purplish red are the most highly valued colors for rubies, subtle variations can mean a noticeable reduction in price and a not-so-noticeable impact on the average person’s perception. For example, an expert can tell the difference between a red and orangish-red ruby, but most people won’t make the distinction.

You can learn to live with rubies that have eye visible inclusions. Eye visible means visible at a distance of approximately 6 inches. That’s very close. Clarity grades of VS to SI cause a significant reduction in ruby prices.

A ruby with a clarity grade of I or lower can still make a beautiful piece of jewelry. It just needs to be worn in an appropriate setting. A stone with inclusions that affect durability may not be a good choice for a ring or bracelet. However, it might do very well as a pendant or earring. (Please note, for any stone, a high hardness score doesn’t mean it’s indestructible. It only means it’s resistant to scratching).

Ruby Buying Caveats

Rubies have been created in laboratories for over a century. Modern techniques for synthesizing rubies can create gemstones that are difficult even for experts to distinguish from natural. The presence of undisclosed synthetics in the marketplace is just one of the things the wary consumer needs to keep in mind.

Synthetic Rubies

Synthetic rubies are real rubies. Chemically and physically they are indistinguishable from natural rubies. This is no consolation, however, if you’ve unknowingly purchased a synthetic ruby at natural ruby prices. Your best defense against purchasing an undisclosed synthetic is to have your new ruby appraised by an independent gemology lab.

Inclusions like the curved striae or lines shown here are a tell-tale sign of synthetic ruby. However, the curvature of the lines can be difficult to see. “Curved Striae” by stonespecialists.
Inclusions like the curved striae or lines shown here are a tell-tale sign of synthetic ruby. However, the curvature of the lines can be difficult to see. “Curved Striae” by stonespecialists.

Simulated rubies, on the other hand, are not rubies at all. Glass or plastic imitations or less-expensive stones that resemble rubies, such as garnets or spinel (and even materials that combine low-grade ruby with glass), are sometimes passed off as genuine rubies.

Colors And Origins

Rubies are found all over the world, and the combinations of trace minerals found at their sources lead to subtle variations in their red color. Because of this, ruby colors are sometimes referred to by country, “Burmese” red or “Thai” red, for example. However, color alone is not enough to accurately identify the source of a ruby. Nevertheless, rubies are sometimes described as “African,” “Burmese,” “French,” “Ceylon,” etc. These trade names for ruby colors misleadingly imply origins.

Ruby Or Pink Sapphire?

Ruby and sapphire are both gem-quality corundum stones. Ruby is the red variety of corundum and receives its color from the trace element chromium. All other color varieties of corundum are considered sapphire. The color pink, a tint of red, straddles the border between ruby and sapphire. However, not all gemologists and jewelers agree on where the boundary lies. You might find your “pinkish ruby” is considered a pink sapphire by one expert but not another. Of course, sapphires are also highly prized and beautiful gems. Pink sapphire has also gained in popularity in recent years. Nevertheless, rubies are still rarer than sapphires. Between stones of similar cut and size, rubies would generally command a higher price. If your ruby buying expedition veers towards pink, be aware of this dispute over definitions.

Treatments And Enhancements

Buyers should assume that rubies have been heat treated unless sellers disclose otherwise. Heat treatments are used to remove rutile inclusions and improve color tone and saturation. Since this treatment is not unlike the natural processes that affect rubies, it does not usually negatively impact price. Other treatments, such as diffusion coloring or filling fractures with polymers or leaded glass, will affect value. For more information on these and other treatments applied to rubies, see our article on Corundum Treatments.

Ruby Buying As An Investment

If you think you’ve found rubies at a bargain price and are considering making a purchase for investment purposes, read this article on investing in gemstones.

“Ruby Drops,” sterling silver and ruby, by Kirsten Skiles is licensed under CC By-ND 2.0
“Ruby Drops,” sterling silver and ruby, by Kirsten Skiles is licensed under CC By-ND 2.0