The Tough Gem: Ruby

Ruby is a species of corundum and ranges in color from orange-red to purple-red. It is medium light to very dark in tone and quite strong in saturation. It is a hexagonal crystal that often comes in six-sided prisms, terminated by flat faces.

Ruby registers a 9 on the hardness scale and is quite tough unlike emerald, and not nearly as subject to breakage. Under long wave ultraviolet, a ruby will fluoresce red or orange-red to inert and under short wave should fluoresce moderate red to orange-red.

Rubies come from a number of areas including Burma, which is usually considered as the finest source of rubies in the world. The best Burma stones are medium dark and vivid red.

Thailand produces stones which are a bit dark in tone and range from purple to brownish red because they have a slight bit of iron in them.  Africa (Kenya, Tanzania) produces stones that are normally highly included although reminiscent of Burma in color. Sri Lanka has occasional rubies but more often sapphires that often mask as rubies.

In the U.S.A., North Carolina and Montana produce a few stones. Australia produces fairly poor quality stones as does India and Colombia, Nepal and Pakistan.

Rubies tend to be valued partially by the country of their origin. Some rubies now come with authenticated certificates of origin and the word Burma will bring a characteristically premium price even when considered next to a Thai ruby that may appear identical to the Burma ruby under incandescent light.

Under fluorescent light, the Burma ruby will appear to fluoresce slightly and take on a deeper saturation. This is a highly sought after quality. Burma rubies also have some fine rutile needles that are commonly referred to as "silk" that add rather than detract to the attractiveness of the stone and further establish it as a Burma stone.

In order to establish a country of origin, a certified lab such as the American Gemological Laboratories in New York, has to study the ruby for body color under various conditions, fluorescence and inclusions. If a ruby is certified as a top Burma ruby, the price may be 1 1/2 or twice what it was as an unknown or as a presumed Thai ruby.

Rubies from Thailand tend to have a brownish or purplish overtone. Those from Sri Lanka are generally very pink in color and more correctly referred to as pink sapphire.

Types of Emeralds

Color is a critical factor in emeralds and constitutes about half of the emerald's value (clarity 30% and cut 20%).

• Hue describes the primary color and any other colors in the stone. Most emeralds are green hued with a bluish hue also visible, especially the better Colombian-type emeralds.
• Tone is the depth or darkness of the color as perceived by the eye.
• Saturation is the amount of hue present in any given color.

Depending upon where the emeralds come from, they can exhibit a wide range of color; i.e., Brazilian emeralds are usually lighter toned and less saturated than their Colombian cousins.

The green in the emerald is caused by the trace element of chromium. If the color is very light green, the stone is more correctly referred to as green beryl, not emerald.

Emeralds are often oiled to help their appearance. Normally an uncolored oil such as Merck cedar wood oil is used. The stone may soak in the oil for several days and will actually take the oil in somewhat, helping bring out the color and "wedding" on some of the dry inclusions, making the stone look better.

If one finds an emerald that is mild in color or has a grayish hue, it is a good bet to soak it in oil a couple days and it may regain its green color, not to mention its value.

A more unscrupulous improvement is to use dye or oil with color in it. It is possible to influence the color of a stone by having it soak up colored oil.

Other problems with buying emeralds are the fact that there are a  number of stones that look like emeralds and overlap colors. Tsavorite, a garnet found in Kenya and Tanzania, looks quite a bit like emerald and has a pure green hue, although it tends to be a little bit more yellowish and never has the blue hue of emerald.

Chrome tourmaline is another stone that looks much like an emerald with a moderately strong green color. Another emerald look-alike comes from Africa and is called chrome diopside. All these stones can, and are, sold as emeralds to the unwary.

Different emeralds from different areas tend to have individually shaped inclusions; i.e., slight pyrite inclusions are typical of emeralds from Colombia although they can be seen in stones from other sources.

A three phase inclusion that shows up under a 10x or stronger microscope, which has a distinctly liquid area, a gas bubble in a solid square rock crystal, salt lying superimposed on each other inside a jagged edged cavity, is typical of emeralds from Colombia and proves their natural origin.

Tropic emeralds from Colombia sometime exhibit six fine radiating arms of black carbon inclusions, spoke-like in appearance.  Another type of this stone has six arms of emeralds extending from the center of the crystal with a white shaped wedge area in between. When these stones are cut and mounted, they are valuable because of their inclusions.

Emeralds: The Gentle Gems

Emeralds are a green crystal of beryllium-aluminum silicate. They are hexagonal prismatic crystal with a hardness of 7 1/2 to 8 on the Mohs scale. They are not tough stones and may be broken easily by mishandling or the use of severe chemicals or ultrasonic cleaners. If you own an emerald, be careful of it. Don't wear it during sports. Don't have a jeweler clean it in an ultrasonic cleaner as it may shatter.

Emeralds also break under applications of heat and should never be in a ring that is soldered. Under ultraviolet light they may fluoresce lightly, orange-ish red to red, or they may be inert.

Emeralds come from a number of sources. The best come from Colombia. These are the purest colored and generally the finest stones. The emeralds from Brazil are lighter, have more inclusions and are generally smaller than from other areas. Zambia, Africa, produces some bluish stones and some near-Colombian stones. Zimbabwe is home to a particular emerald known as the sandawana emerald which is generally small with a rich green color. Anything over 1/3 carat is rare.

South Africa produces some low-quality emeralds. Tanzania produces a few very good quality emeralds. Pakistan has just discovered some high-quality emeralds. Afghanistan tends to produce flawed but good colored emeralds. Russia does produce emeralds but doesn't like to let them out of the country.[1] Australia produces some dubious quality emeralds and North Carolina a few gems. Austria and India occasionally produce emeralds.

Emeralds are not unusual as the word emerald simply indicates an extremely nice version of a fairly common stone known as beryl. It is possible to buy something legitimately called an emerald for about $5 a carat. Obviously this is full of flaws, not transparent and so impure in color it looks more like jade than an emerald. They would never be sold in a jewelry store but emeralds do sell on TV and some of the better magazines for $5 per carat.

Gem quality emeralds range anywhere from $400 to $20,000 a carat, depending upon their quality. As the stones get larger, they become increasingly rare and sell for considerably more money.

[1] This is dated; I do not know the exact laws as of today.

How to Avoid Precious Stone Scams

Dealing with small objects of high value such as precious stones, it's not surprising to find there are a number of creative ongoing scams. The most obvious, of course, is simply to sell a less valuable stone in a more valuable rating. We have seen, in the case of diamonds, how even though subjective, a small difference in the rating can make a large difference in the price. Again, never buy mounted stones.

Substitution of less valuable stones is an offshoot of this where colorless topaz may be substituted for diamonds since most stones are colorless and have quite a bit of luster. The specific gravity of the topaz will approach that of a diamond. Of course, it won't pass other tests for a diamond.

Yellow quartz is often substituted for a yellow diamond. Red spinel is often offered for ruby. The worst examples of this occur in areas where the real stones are found.

Natural emeralds sold on the streets of Colombia, Peru and Brazil are often made from the bottoms of 7-Up bottles.

Sometimes diamonds are manipulated by taking a yellow diamond and super polishing it to look white. On occasion oil may be rubbed in to make it whiter.

Burma, India, Ceylon, Brazil, Peru and even Hong Kong and Thailand are notorious places for substitution of non-gem materials in gem sales.

Sometimes cut stones in upper and lower portions are cemented together. This is known as a doublet. It is possible to take two diamonds, the upper portion one and the lower of another and cement them together to create one diamond without the inherent flaws that the opposite piece had before the fusing process.

It is also possible, and is almost as common, to find the upper portion of a doublet is genuine while the lower portion is cut from a comparatively worthless material such as quartz or glass and then glued. If this is done with a great amount of skill, it will have the appearance of a single stone. It is legal to combine things such as diamonds, rubies, and sapphire doublets if they are not sold fraudulently.

The stone may be dropped in water or acetone and if it's a glued doublet, the glue will dissolve and the stone come apart. However, if glass has been used that's been fused to a diamond top, this will have no effect and the fusion must be found by careful, microscopic examination. This fraud is extremely difficult to detect.

A better test is to immerse the stone in a strong, refracting liquid such as methylene iodide. This is diluted until suddenly one part of the stone becomes invisible. This occurs when the refraction index of a liquid is the same as that of the stone and the quartz portion which has a much lower refraction number becomes invisible, leaving the diamond portion visible. This is an indication of a double stone. Indian jewelers are especially known for their production of such doublet stones.

For the extremely naive, it is possible to buy a false doublet. Here the color of the lower portion is imparted to the upper harder portion but neither party may be gem quality. This is when a piece of rock crystal quartz, a rather colorless stone, is used or glued to colored glass or colored stones. In this case, the top part will take on the color of the bottom part, although neither one is a gem stone. Extremely cheap doublets have been passed off by using simple colored gelatin or coloring and quartz or glass and a bit of glue.

Besides these tricks designed to use modified stone, there are scams such as examining a stone or piece of jewelry and having a second made to match and swapping the two. This can be done when someone goes to answer a newspaper ad, does not buy it but takes a picture or impression of it. Then his friend makes the phony and goes to "examine" the piece and switches the new for the old.

It may also be discovered a stone has been replaced with CZ after the piece was left for cleaning or appraisals.

Faked stones mounted in jewelry and then hocked is the oldest game in the world. The perpetrator runs out of money, offers to leave his precious ring as a security until he can get the money he borrows back to the person. The person may or may not skip with the stone, feeling he has the $5,000 ring.

Lab Created Gems

There are a couple of different systems for forming synthetic rubies and emeralds. One is to use a seed chip of the natural stone and then combine chemicals, heat and pressure to "grow" rubies and emeralds. The latest processes are known as flux processes, which combine heat and/or pressure to work on the ingredients composing the gemestone to be synthesized (The ingredients are fairly easy to come by; i.e., carbon for diamonds or beryl for emeralds).

These flux processes are designed to produce richly colored stones and almost always do. They usually have greater clarity than the natural variety although sometimes offer distinguishing inclusions which telltale their origin.

The most famous emeralds are probably Chatham synthetics which grow in a group of crystals. They were first grown in 1935 by Caroll Chatham of San Francisco. The Chatham family still grows these gems but doesn't care to discuss the process. The Chatham emerald sometimes has small spicule inclusions on the face of the facets as a result of the crystal forming solution.

Gilson is another variety of snythetic emerald. There is also a Japanese gentleman by the name of Kazuo Inamora, President of Kyoto Ceramics, who has three showrooms in Japan and one in Beverly Hills selling "created" rubies and emeralds. These created stones have caught on quite well in other countries including Japan and may or many not catch on here. The price difference between the synthetic and the natural stones is quite great.

Once again, we've had experience with Chatham's emeralds and have had a number of gemologists that had great difficulty telling the natural emerald from the Chatham emerald. In many cases, they both would have passed off as natural stones.