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RUBY

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Ruby

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Mar 1, 2020

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Section 1

(21 cards)

Description

Front

Ruby is the most valuable variety of the corundum mineral species, which also includes sapphire. Rubies can command the highest per-carat price of any colored stone. This makes ruby one of the most important gems in the colored stone market. In its purest form, the mineral corundum is colorless. Trace elements that become part of the mineral's crystal structure cause variations in its color. Chromium is the trace element that causes ruby's red, which ranges from an orangy red to a purplish red. The strength of ruby's red depends on how much chromium is present—the more chromium, the stronger the red color. Chromium can also cause fluorescence, which adds to the intensity of the red color. The most renowned rubies, like those from Myanmar, the Himalayas, and northern Vietnam, typically form in marble. They're found in layers that are distributed irregularly within the surrounding marble. Marble forms as part of the metamorphic (rock-altering) process, when heat and pressure from mountain formation act on existing limestone deposits. Marble has low iron content, so the rubies that originate in marble (called "marble-hosted" by gemologists) lack iron. Because of this, many have an intense red color. In addition, rubies found in marble typically fluoresce red under ultraviolet light—even the ultraviolet light in sunlight. Fluorescence can make a ruby's color even more intense and increase its value. In other locations, rubies can be found in basalt rocks. Rubies from these sources can have higher iron content, which can make the rubies darker and less intense in color. Higher iron content in the chemical makeup of a ruby can also mask the red fluorescence, eliminating that extra glow of red color seen in marble-hosted rubies.

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Color

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- Red to Purplish Red - Chromium is the trace element that causes the red color - Most significant factor in determining quality

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Birefringence

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0.008 to 0.010

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Mohs Hardness

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9

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Cut

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- Commonly fashioned as mixed cuts, oval or cushion - Brilliant-cut crowns and step-cut pavilions - Crystal shape dictates its suitability for certain cuts. The most common shape is a flat tabular hexagonal shape, but ruby crystals from some sources can be elongated. - To accommodate these crystal shapes, the most common shapes of fashioned rubies are ovals and cushions, with brilliant-cut crowns of kite-shaped and triangular facets, and step-cut pavilions with concentric rows of rectangular or square facets. - Round, triangular, emerald-cut, pear, and marquise rubies are also available. But these shapes are rare in larger sizes and higher qualities. - Ruby rough is very expensive, so cutters try to conserve as much weight as possible. They might fashion flattened ruby rough into shallow stones, even though light escapes through flattened pavilions, causing an unattractive see-through area in the stone called a window. - Pleochroism—the appearance of different colors in different crystal directions—is another factor that influences cut. In ruby it typically appears as red to purplish red in one crystal direction and orangy red in the other. Cutters can minimize the orangy red color by orienting the table facet perpendicular to the long crystal direction. Even so, it's not always possible to orient a ruby for ideal color return because the potential loss of weight would be too great. -Taunggyi, Myanmar, a center for cutting using traditional non mechanized set ups

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Synthetics

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- FLAME FUSION OR VERNEUIL PROCESS (MELT PROCESS) The first commercially successful synthetic gems were created by the flame fusion process. This process involves dropping powdered chemicals through a high-temperature flame, where it melts and falls onto a rotating pedestal to produce a synthetic crystal. Today it remains the least expensive and most common way to make gems such as synthetic corundum and spinel - CRYSTAL PULLING OR CZOCHRALSKI PROCESS (MELT PROCESS) Pulling emerged in the early 1900s. In this process, nutrients are melted in a crucible and the synthetic crystal grows from a seed that is dipped into the melt, and then slowly pulled away from the melt as it grows. Gems synthesized by pulling include synthetic alexandrite, chrysoberyl, corundum, and garnet. - FLUX GROWTH (SOLUTION PROCESS) Today some synthetic gems, such as emerald, ruby, sapphire, alexandrite, and spinel can be created through a flux-growth process. Flux is a solid material that, when melted, dissolves other materials in the same way that water dissolves sugar. As the dissolved chemical solution gradually cools, synthetic crystals form. Growing a synthetic gem by the flux method requires patience and significant investment. Crystal growth can take up to a year, and the equipment is very expensive. But the results, especially when it comes to emerald, are well worth the time and effort. - HYDROTHERMAL GROWTH (SOLUTION PROCESS) Like the flux process, the hydrothermal growth process is slow and expensive. But it's the only method for successfully growing synthetic quartz. This process requires heat and pressure and imitates the conditions deep in the earth that result in the formation of natural gems. Nutrients are dissolved in a water solution, and then synthetic crystals form as the solution cools. While the following list encompasses the commonly seen synthetics, over the years there have also been experimental synthetic gems. These include malachite, color change synthetic spinel and others. But because nature produces these products more readily, they are not often seen today. Some of the synthetic gems that are more frequently encountered include: SYNTHETIC CORUNDUM (WIDELY AVAILABLE) Synthetic corundum, which includes ruby and sapphire, can be made by the greatest number of processes. Because of this, synthetic corundum is available at many price levels, from very affordable to very expensive. Ruby - in the late 1800s, ruby became the first gem to be created in a laboratory by Auguste Verneuil. In 1902, he announced the development of his flame-fusion process for synthesizing this beautiful gem.

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Anniversary

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15th and 40th

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Simulants or Imitation Gem Materials

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- The jewelry industry uses special terms for manufactured and look-alike gemstones: synthetic and simulant. The differences between them are subtle, but very important. Synthetic refers to a manmade material with essentially the same chemical composition, crystal structure, and optical and physical properties as the natural gem material. There are also materials that simply look like natural gems. These products are called simulants or imitations, and can be either natural or manmade. Substitute is an older term for the same thing. - MAN-MADE SIMULANTS Quench crackled quartz - Natural colorless quartz can sometimes be subjected to thermal shock, known as "quench crackling." The colorless material is first heated, and then subjected to quenching in a cold, liquid solution—such as water. The sudden contraction causes the material to develop a series of cracks that radiate throughout. Because these are surface-reaching fractures, the quartz can then be subjected to additional immersion in a dye solution, allowing the fractures to be filled with colored liquid. This makes a convincing simulant to such natural gems as emerald, ruby and sapphire, although the fractured and dyed appearance can quickly be seen under the microscope. Prevalence: occasional.

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Where is it Found

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Afganistan - Jegdalek (plagued with war and security and government issues Greenland - (Fiskenaesset Ruby Project) not yet in commercial production - in-situ sources, meaning the ruby is still located within the original hard rock. Kenya - Rockland Ruby Mine in South Tsavo National Park mechanized operation for processing and sorting Madagascar - prolific production Malawi - Chimwadzulu Hill produces ruby as well as pink, purple, and orange sapphire Mozambique - potential for large supply. Previously mined by independents illegally. Mining company Gem Fields will now mine with a government partnership Myanmar - (formerly Burma) Mogok Valley - most famous and best quality Nepal - no significant stones found Pakistan - Hunza Valley Sri Lanka - primarily known for Sapphires Tajikistan - intense red rubies Tanzania - significant colored stone deposits Thailand - Cutting and Trading no longer mining Vietnam - new to mining similar quality to Myanmar

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Specific Gravity

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4.00 (+/- 0.05)

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History and Lore

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Red is the color of our most intense emotions—love and anger, passion and fury. It's associated with objects of power and desire—like fast cars and red roses. Early cultures treasured rubies for their similarity to the redness of the blood that flowed through their veins, and believed that rubies held the power of life. Ruby is one of the most historically significant colored stones. Rubies are mentioned four times in the Bible, in association with attributes like beauty and wisdom. In the ancient language of Sanskrit, ruby is called ratnaraj, or "king of precious stones." In the first century AD, the Roman scholar Pliny included rubies in his Natural History, describing their hardness and density. Ancient Hindus believed that those who offered fine rubies to the god Krishna were granted rebirth as emperors. Hindus divided ruby into four castes, calling the true Oriental ruby a Brahmin. Someone in possession of a Brahmin was believed to have the advantage of perfect safety. Ruby has accumulated a host of legends over the centuries. People in India believed that rubies enabled their owners to live in peace with their enemies. In Burma (a ruby source since at least 600 AD—now called Myanmar), warriors possessed rubies to make them invincible in battle. However, it wasn't enough to just wear the rubies. They had to insert them into their flesh and make them part of their bodies. The name ruby comes from the Latin word ruber, which means "red." The glowing red of ruby suggested an inextinguishable flame burning in the stone, even shining through clothing and able to boil water. Ruby has been called the most precious of the 12 stones created by God. Ruby retained its importance with the birth of the western world and became one of the most sought-after gems of European royalty and the upper classes. Many medieval Europeans wore rubies to guarantee health, wealth, wisdom, and success in love. Desire for ruby is just as great today as it always has been. As a symbol of passion, ruby makes an ideal romantic gift. Consumers are drawn to the lush color because it also signifies wealth and success.

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Birthstone Month

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July

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Treatments

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Fracture or Cavity Filling - Numerous surface-reaching fractures are filled with a glass to lessen their visibility and make the gem more transparent than it really is. In some cases, the amount of filler glass can be significant in a treated ruby. - Heat Treatment - Heating can remove purplish coloration rendering a more pure red color. The process can also remove "silk" (minute needle-like inclusions) that can cause a gem to appear lighter in tone and be more opaque. Heating can also cause recrystallization of the silk inclusions to make them more prominent which allows the gemstone to have stronger asterism (a reflecting star effect). - Lattice Diffusion - while experimentation during the 1980s concentrated on diffusion of titanium and chromium (which are coloring agents in corundum), the ability to fully penetrate the stone with color met with little success. In 2003, very strongly colored sapphires began to appear in the market, and diffusion was again suspected. It was found that it was diffusion — but of a new element: beryllium. Beryllium which has a much smaller atom than titanium or chromium, was able to diffuse all the way through a sapphire; even large sapphires, successfully changing their color. It was soon found that the color of rubies could be accentuated as well using this treatment process.

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Buyers Guide

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- COLOR IS THE MOST IMPORTANT QUALITY FACTOR FOR RUBY The finest ruby has a pure, vibrant red to slightly purplish red color. As the color becomes too orangy or more purplish, the ruby moves down in quality. The highest-quality rubies have vivid color saturation. The color must be neither too dark nor too light to be considered finest quality. - CLARITY REFERS TO THE INCLUSIONS People in the trade expect rubies to have at least some inclusions because inclusion-free rubies are rare. Ruby value depends on how visible the inclusions are. Obvious inclusions or inclusions that reduce transparency or brightness lower a ruby's value dramatically. - CUT IS ONE OF THE MOST IMPORTANT FACTORS IN APPEARANCE Several factors affect the cut and proportion of rubies on the market. A ruby's crystal shape dictates its suitability for certain cuts. The most common shape is a flat tabular hexagonal shape, but ruby crystals from some sources can be elongated. - CARAT WEIGHT ALLOWS FOR PRECISE MEASUREMENTS Fine-quality rubies over one carat are very rare, but commercial-quality rubies are commonly available in a wide range of sizes. The price per carat goes up significantly for ruby as it increases in size.

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Forms

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- Metamorphic process inside coase grained marble

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Carat Weight

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- Fine-quality rubies over one carat are very rare, but commercial-quality rubies are commonly available in a wide range of sizes. The price per carat goes up significantly for ruby as it increases in size. - For example: A commercial-quality 5-carat ruby might sell for about twice as much per carat (10 times total stone value) as a commercial-quality 1-carat ruby, while a fine-quality 5-carat ruby sells for over five times more per carat (25 times total stone value) than a fine-quality 1-carat ruby. - These examples are not meant for exact pricing guidelines, but to illustrate how much the per-carat price can go up as the size and the quality rise.

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Chemical Composition

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Al2O3

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Mineral

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- Corundum

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Clarity

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- Inclusion free rubies are basically non-existent - Value depends on how visible the inclusion is - Obvious inclusions or inclusions that reduce transparency or brightness lower a ruby's value dramatically - If large and prominent inclusions are located under the table facet, they greatly diminish the transparency, brilliance, and value of the stone - Inclusions can also limit a ruby's durability. Significant surface-reaching fractures can pose durability threats - - If inclusion affect its transparency or brilliance, it decreases its value - Silk Inclusions - intersecting needles - when intact, they prove the stone was not heat treated by very high temperatures. Low temperatures could still have been used. Needles might be short or long and slender, and they might appear to be woven tightly together. - May also contain needles composed of other minerals, small crystals, zones of color variation, or inclusions that resemble fingerprints - Some inclusions can actually contribute positively to a gem's appearance. The presence of rutile silk causes light to scatter across facets that might otherwise be too dark. This adds softness to the color and spreads the color more evenly across the ruby's crown - Needles that intersect can also cause the star effect, called asterism, when the stone is cut with a curved upper surface

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Journey

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Few people outside the gem industry realize the true nature of a gemstone's journey from the mine to the counter of a store. Whether the gem is being offered to consumer's at a traditional jewelry store's counter, an internet shopping site, or a television broadcast the journey always involves a great deal of effort. Tons of earth and countless hours of labor are needed to being a gem from mine to market. - Most ruby deposits and mines in the world consist of rubies that are found in alluvial sources - this means that natural erosion and weathering has extracted the gems from their host rock and concentrated them into rivers and streams. The resulting rubies are generally rounded in shape due to weathering during transport and are often of a high quality because the weathering preferentially erodes the softer non-gem material. Mining rubies from alluvial sources is a relatively simple process, as the difference in specific gravity (weight) between ruby and other minerals (sand) allows them to be separated by gravity in much the same way as gold is separated while panning.

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Refractive Index

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1.762 to 1.770

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