How Do I Choose Investment-Quality Rubies?

The first thing to consider when buying a ruby is its place of birth. By general agreement among gem experts, the world's best rubies come from Myanmar (formerly known as Burma), specifically the region around the town of Mogok. Gem buyers need special permits to buy stones in Mogok or even visit this area, so most foreign investors need to visit licensed gem dealers in other Asian capitals, including Yangon and Bangkok. Sri Lanka also offers high-quality gemstones, while Thailand and Vietnam produce the "commercial-quality" stones that are sold at retail outlets throughout the world.

Gemstones such as rubies, emeralds and sapphires are graded on their color, clarity and brilliance. Rubies and sapphires are, in fact, the same mineral (conundrum); the only difference is their color. A deep and vivid red color is the mark of the best-quality ruby, while lighter-colored and dark, purplish stones are considered to have less value. Although degrees of redness are a subjective measurement, eventually the lighter-colored stones are properly called "pink sapphires." The widely accepted measurement of these qualities is known as the Gemological Institute of America (GIA) scale.

Clarity and brilliance are the other factors in a ruby investment. These are subjective measurements, but generally the more clear and bright the stone is to the naked eye, the more valuable it is. A transparent ruby would be the most valuable of all, as well as the rarest. Clarity and brilliance are enhanced by cutting the stone and setting it so that it captures and reflects light to its best potential.

Synthetic rubies have been on the market for more than a century. Natural stones, of course, are more valuable than artificial stones, but the difference is not really clear to an untrained buyer or the naked eye. Artificial rubies are heat-treated, a process that fractures the base material and also creates tiny gas bubbles. Examining the stone through a photographer's loupe or microscope will reveal these faults. When browsing for rubies anywhere in the world, remain aware of the artificial stones that have flooded the market and bring your loupe or magnifying glass along.

Modern gem dealers commonly heat-treat their rubies to enhance the color and clarity of the stones. While low-temperature heat treatment does not affect the quality and value, a different process, known as "bulk diffusion," heats the stones to extremely high temperatures and pressure, while adding coloring agents to alter their natural appearance. If the stone is scratched, the underlayer of genuine color will appear, ruining the consistency. There is no way to know if your ruby has been heat-treated this way other than to trust the dealer's word, so for this reason, among others, you should only deal with reputable dealers and be highly suspicious of any surprisingly cheap stones offered via Internet sites.