Ruby Guide

Rubies are made of the same mineral as sapphires, namely corundum, and measure a 9 on the Mohs gemstone hardness scale (second only to diamond).  Ruby color quality is judged on three factors - hue (color), saturation (the strength or weakness of the color), and tone (the lightness or darkness of the color).

When you’re shopping for ruby jewelry, keep in mind that the more pure and vivid the ruby color, the more valuable (and expensive) the ruby.  Rubies from the Mogok Valley in Burma, for example,  are known for their quality and ‘pigeon blood’ color and are  quite expensive. 

A very important ruby jewelry shopping tip:  Unlike sapphires, where a natural, untreated sapphire is readily available provided you can afford one, a search for a natural, untreated ruby may be more difficult.  Read on to find out why – it’s important that you understand the why before you buy.

 
Heat-Treated Rubies/Enhanced Rubies.  It’s an acknowledged fact (acknowledged, in fact by the Gemological Institute of America) that the majority of rubies have undergone heat treatment to improve their clarity and/or color.  A heat-treated ruby can only be detected by a gemologist and even if heat treatment isn’t detected, it is so prevalent in the industry that it is assumed that ruby jewelry has been heat treated.

Heat treated rubies are no less stable than untreated rubies; however, should your ruby jewelry ever require repair or altering, it is important to let your jewelry know that your ruby jewelry is heat treated.

Other Ruby Treatments.  Other, less prevalent ruby treatments include surface diffusion, fracture-filling (with oil or epoxy resin) and cavity-filling (with epoxy resin or glass). 

Surface diffusion (heating the ruby to a very high temperature in the presence of a coloring agent) applies a shallow layer of red coloring in an otherwise light colored or colorless sapphire (remember, rubies are the same thing as sapphires, only red).  The resultant red color of surface-diffused rubies is stable and permanent under normal conditions but can be damaged and destroyed if the gemstone is recut or repolished. 

Fracture-filling is used on occasion to improve a ruby’s clarity.  Using colored oil or resin to fill minute fractures in the ruby also enhances its color.  The resultant stability of a fracture-filled ruby is ‘fair’, because exposure to heat and chemicals can damage or destroy the filling agent used on the ruby and an oil filling agent will probably discolor and dry out over time.

Cavity-filling improves a ruby’s clarity by hiding cavities.  This ruby treatment is fairly common and results in a ‘fair’ stability rating, as heat and chemicals can damage or destroy the filling.

What is a Lab-Created/Synthetic Ruby?  A lab-created or synthetic ruby, like other lab-created gemstones, has all the chemical properties and physical characteristics of a natural ruby and can only be distinguished from a natural, non-lab-created ruby, by a trained gemologist.  And, as with natural gemstones, lab-created gemstones can be of high quality or lesser quality.

There are two predominant methods by which lab-created/synthetic rubies are made:  Flame fusion and heat flux.

Flame fusion is a quick and cheap method to produce lab-created rubies.  Because our focus is ruby jewelry rather than gemstone chemistry, we won’t go into the details of the process, except to stress this:  Flame fusion produces lower quality lab-created rubies, suitable for costume jewelry, class rings and lower-end fine jewelry pieces.

Heat flux, which can take up to six months to produce a gemstone, results in lab-created/synthetic gemstone-quality rubies.

As mentioned several times throughout this website, the FTC (Federal Trade Commission) requires that a jewelry dealer disclose any enhancement treatments your ruby jewelry, or other gemstone jewelry, has undergone.  The FTC also has strict definitions for what constitutes a lab-created/synthetic gemstone.  If you want to read more, check out our Jewelry Reference Links page.  These strict requirements, by the way, are known and understood by reputable jewelry dealers, who will clearly and voluntarily disclose any enhancement treats undergone by the ruby jewelry or other gemstone jewelry you buy.

 Ruby Jewelry Shopping Tips:

• Look for clear, unclouded rubies with deep, vivid color.  Avoid clouded stones.
• Know that your ruby jewelry has probably undergone some kind of enhancement process.  Make sure you clearly understand your ruby’s enhancement treatment and the subsequent care you need to take with your ruby jewelry
• Lab-created/synthetic rubies have the same properties as natural rubies and are more affordable.  If you opt for a lab-created or synthetic ruby, be sure you know by which method your ruby was produced (see above, flame fusion v. heat flux).  By and large, reputable fine jewelry dealers will clearly disclose any and all information you need to make an informed ruby jewelry purchase.  If not, just ask!  If you get no response or an unsatisfactory response, move on!