Rubies and their availability

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Ruby is red corundum, all other color varieties of corundum being

referred to as sapphire. The ruby color range includes pinkish,

purplish, orangey, and brownish red depending on the chromium and

iron content of the stone. The trace mineral content tends to vary

with the geologic formation which produced the ruby, so original

place designations such as Burmese and Thai have come in later years

to be sometimes used in describing color.

.... Most authorities expect a medium to medium dark color tone in a

ruby, naming stones lighter than this, pink sapphire -- but there is

no general agreement exactly where the line is to be drawn. The old

joke about questionable stones goes: "Whether it's a ruby or a pink

sapphire depends on whether you're the buyer or the seller."

.... All corundum gems including ruby have a long history of

enhancement. Unless the seller specifically states the stone is

unheated, you should assume that some kind of heat treatment has

been used. Usually high temperature heating and controlled cooling

is done to clarify the stones, especially by dissolving "silk"

(rutile); but it can also improve tone and saturation of color. Such

treatments can only be detected in stones whose residual inclusions

show signs of heat stress; truly clean stones will give no clues and

cannot be verified as natural color. The general view at present

seems to be that simple heating, being indistinguishable from

Nature's own heating processes, and stable, is acceptable -- as long

as it is disclosed. For this reason such enhancement does not

radically lower the value of ruby gems. Not so for other more

recently invented treatments such as diffusion coloring, or polymer

or glass filling.

.... Corundum was first synthesized in the early 1900's by a simple

flame fusion process. Many jewelers and gemologists have had the

unpleasant task of telling the proud heir that Grandmother's

treasured ruby ring or brooch contains a flame fusion stone and has

a lot more sentimental than commercial value. More complex synthesis

processes have been developed in recent years. These so closely

simulate natural formation conditions that colors and even

inclusions look extremely natural and such stones are difficult for

all but the most highly skilled professionals to identify as man-

made.

.... Ruby is hard (9) and tough, making it a superb jewelry stone.

(Of course, a heavily included or fractured stone will be less

stable.) For reasonably clean stones, no special wear or care

precautions are necessary. Ruby shows pleochroism which means that

the color varies with the direction of viewing. Most stones show

purplish red and orangey red, although the presence or absence of

trace minerals can dampen either of these. The overall color can

often, but not always, give a clue to a stone's geographic origin,

with Burmese stones tending to purplish red colors and Thai stones

appearing more brownish red. In addition, many rubies will fluoresce

in long or short wave UV and this property can often be used to help

identify a stone's geographic origin. Burmese rubies often fluoresce

so strongly that the effect is noticeable even in sunlight, such

stones seem literally to glow, and are greatly admired. Thai stones

generally lack this property. Although Asia has historically been

the major producer of ruby gems, there are many other sources

including the USA, Australia, and most recently Africa.

...Ruby rough of lower quality is used in great quantities to make

beads, carvings, and other ornamental objects. The silk, which is so

common in corundum, can, if sufficiently abundant, and precisely

arranged, lead to asterism. With proper cutting, this creates star

rubies. Today there are heating and diffusion processes that can

increase the rutile content and improve such gems. Synthetic star

corundums were very popular in the 1950's under the trade

name "Linde Stars" and are still under production.

.... Few other gems have as much myth, lore and romance surrounding

them, with one of the chief attractions being the protection from

misfortune and bad health rubies were believed to afford their lucky

owners. As the science of gemology developed it became known that

many historically important "rubies" such as the famed Black

Prince's Ruby of the British Crown Jewels, were actually other red

gems, most often red spinels.

 

 

Value:

.... Rubies are the most valuable members of the corundum family.

Large gem quality rubies can be more valuable than comparably sized

diamonds and are certainly rarer. There is a relative abundance of

smaller, (1-3 carat,) blue sapphires compared to the scarcity of

even small gem quality rubies, making even these smaller stones

relatively high in value.

.... Stones of Burmese origin generally command the highest prices.

The vast majority of rubies are "native cut" in the country of

origin. High value ruby rough is tightly controlled and rarely makes

its way to custom cutters. Occasionally, such native stones are

recut to custom proportions, albeit at a loss of weight and

diameter. Custom cut and recut stones are usually more per carat,

and my own bias is that they are worth it.

.... Sinkankas and Miller in the Standard Catalog of Gem Values, 2nd.

Ed. list a wide range of wholesale prices for faceted gem rubies.

Prices are dependent on origin, color, size, and clarity: from a low

of $100 to $15,000/ ct maximum.

.... Burmese stones in 1/2 to 1 ct sizes with slightly purplish red

color and light inclusions range from $300 to $3000/ ct, for

example. The price survey done by the International Gem Society

reports that clean, top color gems in the 1/2 to 1 ct size range are

being sold, retail, on the Internet with a range of $1000 - $3000/ct

 

 

 

 

 

 

 

 

 

 

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