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All About Star Rubies

R2816 | left | medium

Stone ID: R2816
Weight: 1.69 carats
Origin: Myanmar (formerly Burma)

Star rubies are amongst the rarest and most coveted gems in the world. Even more so in comparison to star sapphires, since the chromium that colors them pink and red limits the sizes they can grow to. Each star ruby is so unique in appearance, that matching pairs (much less a set) is nearly impossible.

Special features that appear in gems like a star are known as phenomena . These effects include asterism , chatoyancy , iridescence, adularescence , aventurescence , labradorescence , and play-of-color . Rubies mainly show asterism, and rarely chatoyancy. It is possible for them to show other phenomena, but this happens only rarely.

The most well-known source of star rubies is Myanmar (formerly known as Burma) due to how the silk forms in a very organized, and tightly knit fashion. Not all rubies display silk like this, or at all, though it is very common.

The 4Cs for Stars

Like most gemstones, star rubies also follow the usual 4Cs of color, clarity, cut, and carat weight. However, the 4Cs for stars are different.

Color – Asterated corundum qualifies as a star ruby as long as it is properly polished with a star, and has any amount of red in it. No red means it is a star sapphire . This means the ruby can have a dominant color of purple, and so long as it has a modifier of red, it is still called a star ruby. It can also be silvery or white with faint amounts of pink and still qualify as a star ruby, though the price will reflect this. In R2773 below there are faint amounts of red present in the edges of the stone, so it qualifies as a star ruby. This rule also means pink star sapphires do not exist by definition.

Cut – All star rubies (and star sapphires) will be cut into rounded forms. The curved surface is what allows for the star to be created. You can even have a star ruby in a sphere shape, though do not expect it to be gem quality unless it is synthetic.

A well-centered star is also one of the most challenging cuts to make due to the 3 dimensional alignment of rutile needles . Beware of perfectly cut and colored star rubies lacking documentation and lab reports. They are most likely synthetic, especially at lower price-points.

R2773 | middle

Ruby ID: R2773
Weight: 6.66 carats
Origin: Myanmar (formerly Burma)

Weight: 60 Carats

Clarity – Lack of visible inclusions is what makes ruby gem material desirable. However, a very specific type of inclusion is what causes the star in corundum.  Because the star needs rutile needles to appear, the best clarity possible in star corundum is semi-transparent. It’s important that there are not too many needles, otherwise the stone can be opaque, negatively impact the color, decrease durability, and other undesirable effects.

The star ruby on the right is an example of having too many rutile needles. The body color is very silvery, opaque, and the red is very purple. This is what natural, untreated ruby material costing less than $1 per carat looks like.

A selection of star rubies side-by-side.

Individual Stars

No two stars are the same, with the stars being as unique as the growth characteristics of the ruby. Sometimes stars are fainter, stronger, or off-centered. The individual arms can be uneven, of different lengths, missing, etc. The way the star moves along the surface of each ruby is unique too. Some move around very smoothly, some do not move much, jump around, disappear entirely from certain angles, and more. Each star really has its own personality in appearance and movement, and makes matching pairs extremely difficult.

Weak Star

Uneven Arms

Strong Star

Thin Arms


Thick Arms

An ideal star would be centered on the ruby, show strongly, move smoothly across the curved surface, reach across the whole top of the ruby, and have all 6 arms, all being of equal lengths.

Because of the extensive grading criteria for the ruby stars and color, the overall standards for quality are more relaxed. Most star rubies either show a better star but a more silvery/white color, or better transparency and color but a weaker star. Nature rarely strikes a good balance between the two, making the rare few rubies that do reach this quality some of the rarest gems in existence.

12 Ray Stars

While unusual, having a natural, double star sapphire or ruby is possible in two ways. The first one is that the silk inclusions in the ruby are re-aligned by twinning in the stone, more plainly phrased as irregularities in the crystal structure due to how it grew. This creates multiple white stars on the same stone. The second possible way is to have hematite needles (less common than rutile in corundum) and rutile needles present at the same time. This forms stars of different colors, one white (rutile needles) and the other yellow (hematite needles). Occasionally they will form with one star overlapping the other, and make a 12-rayed star with both white and yellow arms.

Generally speaking, this is not probable with gem quality rubies. For a star to be visible, it requires a certain amount and type of inclusions. The more inclusions required to create certain phenomena, the lower the likelihood that the stone is high quality. Stars with hematite and rutile will most likely be opaque black-star sapphires, though double-star rubies with these inclusions are technically possible.

Synthetic Star Rubies

Example appearance of a common synthetic star ruby.

Like normal rubies, synthetic star rubies can be created. There are two types; one where synthetic rubies are diffused with stars, and the other has natural rubies diffused with stars. In both cases the new, synthetic rutile needles will be confined to the surface unlike natural stars. They are formed by rutile needles inside the ruby as shown below. Natural ruby material will be heated in this case too, though heating by itself is not an indication of a synthetic star since most rubies are heat-treated.

Natural silk in a ruby from Mogok, Myanmar (formerly Burma)

While only a 2D image above, many synthetic star rubies look like they have a white star painted on, along with round rings on the bottom of the base. Some companies do make higher-quality, translucent star rubies.

Synthetic rubies are unique in that any repolishing or chipping will remove the star or parts of it from the ruby. Just like the process of diffusing color, diffusing rutile needles work from the outside to the inside, meaning the treatment does not penetrate through the whole stone.

Heated Star Rubies

While technically not synthetic, natural rubies with enough rutile needles in them can be heated to make the rutile recrystallize and show a star. They share the same problems as synthetic stars with losing the star to possible chipping and repolishing.

Some people also treat gem material with stars to show better color, though this is a painstaking process since the silk will dissolve at high temperatures. The vast majority of star rubies will be unheated, and the ones that are should also be checked by a lab for a synthetic star.

Famous Star Rubies

Fine-quality rubies are rare as it is, with few that reach appearances that are the stuff of legends.

Name: Delong Star Ruby
Weight: 100 Carats

The Delong Star Ruby is the first example. The star arms are very straight, reach across the ruby from edge to edge, and are even lengths.

For a ruby this size, a star of this quality is almost unheard of. Furthermore, the ruby is semi-transparent, meaning it shows the best possible transparency a star ruby can show. All of this in combination with perfect color with it’s hue, tone, and saturation.

The Delong does have a couple of small blemishes. That is visible in the photo, but the 99% clear appearance otherwise is world-class in terms of rarity. Additionally, these “blemishes” (formally called clarity characteristics in the gemological community) enable identification by gemologists, and are used to check for signs of treatments.

The Rosser Reeves Star Ruby is another one-of-a-kind, world-class star ruby.

Name: Rosser Reeves Star Ruby
Weight: 138.7 Carats

This one was also involved in a high-profile theft from the American Museum of Natural History in 1965 by Jack Roland Murphy, Allen Khun, and Roger Clark. Incidentally the museum windows were left unlocked anyways, case lids lifted off with a screwdriver, and the immediate alarm turned off by an under-paid and bribed security guard. A number of other gems had been taken too, including the Star of India, a gem-quality sapphire over 500 carats.

After being caught Khun pleaded for leniency and led officers to where the gems were being held; a coin locker in a Miami bus station. Most, but not all had been recovered. Furthermore all these world-class gems had not been insured.
Before the gem heist; the last private owner, Rosser Reeves, would carry this ruby around in his pocket. It was almost lost in the back-seat of an NYC Taxi on one occasion.

Smokey Mountain Star Rubies

Looking at a world map, you will find that most gem-quality rubies come from around the edge of the Indian Ocean, with a few other low-production areas around the globe.

North Carolina will never be listed from these sources, yet managed to produce not one, or two, but four fine-quality semi-transparent star rubies with some of the most perfect stars ever seen. The Smokey Mountain Two Star Ruby of which shows two stars (one on the top, one on the bottom).

Order left to right: The Misty Star Ruby (52.37 Carats), The Appalachian Star Ruby (139.43 Carats), The Smokey Mountain Two Star Ruby (86.56 Carats), The Promise Star Ruby (64.17 Carats)

While rubies like the Delong show better quality overall with less-visible growth zoning, its star is not as high-quality. The Misty Sar Ruby has the most unique profile of the group as a pear-shaped cabochon. The Appalachian Star Ruby is the largest of the group and went on display at the Natural History Museum in London, drawing some of the largest crowds the museum has ever seen.

Cutting stars in rubies is very, very difficult. The fact that both Smokey Mountain Two Star Ruby has two well-centered stars is phenomenal. By comparison the Promise Star Ruby is a little boring. However, its circular shape shows how even and straight all its arms are. Seeing a perfect star with a perfect shape is a rare treat.

Rajaratna Star Ruby – A fine-quality double-star ruby weighing 1,370 carats. This ruby is reportedly of top-quality appearance, with rumored price quotes of $100 million dollars. Unfortunately information on it is limited due to being in private possession of G. Vidyaraj. He also has other world-class rubies in his possession.

There is a story to accompany this perfect collection of rubies. Supposedly Vidyaraj is a descendant of the last Hindu dynasty to rule the Vijayanagara Empire in South India. While the family was still in power, they collected sacred items known as “Shaligram” as a symbol of Vishnu in certain sects of Hinduism. Shaligram are also colored black. These black rocks continued to be worshipped as sacred objects in the family, including their eventual flight from the declining empire and new life as farmers.

As an individual not as concerned with religion as his wife and family, Vidyaraj eventually started to clean these sacred items when home alone with soapy water and a toothbrush. This led to the discovery of a distinct, bright red patch of color underneath. With sufficient research he decided to have the not-Shaligrams cut, which revealed world-class star rubies of impeccable quality.

Unfortunately there are no public photos available to show these rubies, though there is documentation to prove that they are very real. It does beg the question of what quality they are. If the appearance does match the price quotes, they may be the most impressive star rubies ever known. The fact that they are all a part of the same collection would make even the wealthiest gem aficionados in the world drool.

Eminent Star Ruby – The largest star-ruby in existence, but not of gem quality. It weighs 6,465 carats or 2.85lbs, and also lacks publicly available photos. Currently owned by Kailash Rawat of Eminent Gems.

When discussing star rubies, they are usually very small and only a few carats large at most in the top-qualities. This is because the element that colors rubies, chromium, physically limits the size they can grow without significant fractures. Aside from the incredibly rare exceptions listed above, rubies never reach gem-quality (much less top-quality) at sizes over 50 carats. Even major auction houses like Sotheby’s and Christies do not usually see star rubies over 25 carats, though private sales might be a separate story.

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