The Big Three

(The first instalment of this article appeared in our issue of June 2-8, 2003.)

Mention “the big three,” and many people will immediately think: Roosevelt, Churchill and Stalin. Or perhaps the younger among us will imagine a burger, fries and a shake. Regardless, the big three are actually ruby, sapphire and emerald, representing the three primary colours: red, blue, and green. Next to diamonds, they are the best known, the most popular, the most widely available, and generally the most expensive of all coloured gemstones. They are also the most widely counterfeited (as discussed in Part 1), but that’s another story.

Actually, these three gemstones comprise only two minerals, as ruby and sapphire are both varieties of the mineral corundum, an alumina oxide. With a hardness of nine, corundum is very durable, has a high lustre, and under certain geological conditions will grow into transparent crystals. If contaminated by trace amounts of chromium, it will turn a beautiful, glowing, deep reddish pink, and be called a “ruby.” If contaminated by trace amounts of titanium, with a wee bit of iron, it will turn deep blue and be known as “sapphire.” Any gem variety of corundum other than ruby is known as sapphire, and any sapphire other than blue (and there are many) should be prefixed by the colour (for example, “purple sapphire,” “yellow sapphire,” etc.). Given that rubies and sapphires are rarely completely transparent, they are commonly heated, which improves their transparency while brightening their colour. Unfortunately, they are often subject to many other treatments as well, and usually these are not disclosed.

The world’s best rubies and sapphires come from a small area in Myanmar, where extra-fine cut stones more than a carat or two in size can fetch retail prices of more than US$10,000 and $5,000, respectively, per carat, even if they have been heat-treated. From anywhere else, prices are about half at the top end but closer as you move down. Rubies and sapphires are also found in Thailand, Sri Lanka, Australia, East Africa, and Montana. Most production is from placer deposits (versus lode), and most mining is carried out on a small scale by small groups of locals who use old, primitive, or manual methods to recover the stones.

However, several companies use modern, industrial methods to explore for and mine rubies and sapphires. Australian miner Cluff Resources Pacific (CFR-ASX), is developing an alluvial ruby deposit north of Sydney, where an inferred resource of 14 million carats has been reported. Similar to diamonds, the size and grade of any deposit are only two of several economic factors, the other main factor being the average value per carat, which in turn is dependent on the average size, shape, colour and clarity of the individual stones recovered. As a result, much more work is required in assessing and developing a gemstone deposit than is the case with most metallic mineral deposits; for example, the price of gold is the same, be it found in microscopic specks or big nuggets, whereas this is most definitely not the case with gemstone deposits.

Anglo Swiss Resources (ASW-V), a Canadian junior, is focused on gemstones in the Slocan Valley area of British Columbia, where it is pursing sapphires, iolite (the gem variety of cordierite), and rhodolite (a pink-red variety of garnet). The sapphire discovery, known as Blu Starr, is being pursued in a joint venture with Hampton Court Resources (HCR-V). The Yogo Gulch area of Montana hosts a major sapphire resource, first discovered by placer gold miners in the late 1800s. It is unique among the world’s sapphire deposits since Montana sapphires lack the colour zoning so prevalent in other sapphires. Their uniform “corn-flower blue” colour is natural (not the result of heat-treating), and their clarity is uniformly high. These features render them among the world’s finest sapphires; unfortunately, the “rough” (that is, the sapphires found in their natural state, prior to fashioning) is typically both small and flat. Mining of Yogo Gulch sapphires began within a year of their discovery in 1895 and continued for 39 years. In 1923, the mine was damaged so badly by rain that recovery became uneconomic. There have been further attempts to mine the deposits commercially, but, to date, all attempts have ended in economic failure (including one by a now-defunct Canadian junior, American Gem).

Elsewhere in the world, Gem Resources, a private company from Madagascar with a branch office in Quebec, is pursuing some of that country’s recently discovered sapphire-rich areas. American Benefits Group (ABFG-O) is also pursuing rubies and sapphires in Madagascar, through several companies in which it owns a major interest.

Gem varieties

Emerald, the green member of this primary-colour triumvirate, has a hardness of 7.5-8 on the Moh scale and is the chromium-coloured gem variety of the mineral beryl (sometimes with vanadium, too), a beryllium silicate; similar to fine ruby, top-grade emerald virtually glows. Other gem varieties of beryl include aquamarine (pale greenish-blue), heliodor (yellow), morganite (pink), goshenite (colourless), and bixbite. Bixbite is an extremely rare red variety found only in the Wah Wah mountains of Utah (Kennecott attempted to commercially mine them). Prices for extra-fine emeralds are generally between those for sapphire and ruby. Among the other beryls, only bixbite comes close in price to emeralds, the king of beryls. Similar to rubies and sapphires, natural emeralds usually contain inclusions and fractures, and as a result, they are often treated prior to being sold, usually with a liquid to fill and thus obscure the fractures (oil or polymer); once again, these treatments are not always disclosed. There are also manufacturers of synthetic emerald, just as there are of ruby and sapphire.

Emeralds have been mined since ancient times, one of the oldest sources being the area near the Red Sea in Egypt. Today, the Muzo and Chivor regions of Colombia produce the finest gems (unfortunately, a Canadian company, Chivor Emerald, attempted to develop and produce emeralds there without success). However, fine emeralds are also found in Brazil, Tanzania, Madagascar, South Africa, India, Pakistan, Russia, North Carolina, and, most recently, the Yukon.

True North Gems

Emeralds were accidentally discovered in the Yukon in 1998 by Expatriate Resources (EXR-V) while that company was exploring for massive sulphides. True North Gems (TNG-V) was founded soon afterwards; the company optioned the claims from Expatriate and has been devoted to the exploration of this spectacular new discovery ever since. Regal Ridge is the name of the original discovery site, where recently True North has carried out trenching and sampling. Additionally, the company has staked six more properties in the general area, where similar geology and other features indicate potential for even more emeralds. Most of these claim groups have been optioned to other Canadian explorers, including: Hinterland Metals (HMI-V), International Arimex Resources and Firestone Ventures. Time will tell if this spectacular discovery can succeed as a commercial mining operation and put Canada on the international emerald map. In the meantime, it is proving to be an exciting exploration play.

Several Canadian companies are pursuing emeralds elsewhere in the world. Rio Verde Industries, a privately owned junior in Vancouver, is buying and selling rough and cut emeralds from Colombia. It is acquiring the rights to several producing and prospective emerald deposits there and hopes to undertake an initial prospectus offering in 2004. Verena Minerals (YVM-T) owns the Rainbow emerald-alexandrite deposit and the Paraiso emerald deposit, both of which are in Brazil. An 8.06-carat trillium-cut emerald recently mined from Paraiso sold at a wholesale price of US$25
,000, which is equivalent to more than US$3,000 per carat, or more than US$15,500 per gram (compared with US$11.57 for an equivalent amount of gold).

So much for the Big Three. The next article in this series will look at some of the more exotic and less-known coloured gemstones being mined around the world. Stay tuned. Meanwhile, be sure to catch the television documentary series Stones of Fate and Fortune, which is about coloured gemstones. It is being produced by the Discovery Channel. For telecast dates, see www.discovery.ca

— Avrom Howard, M.Sc, P.Geo, FGAm is a geoscientist and certified gemologist. He may be reached at avromeric.howard@utoronto.ca