While most likely known by a large population of jewelry collectors, not everyone is familiar with the fact that sapphires can actually come in a wide variety of colors. Let's start first with a little bit of basic chemistry- Aluminium oxide (Al2O3) that naturally crystallises in the trigonal atomic lattice system forms as a gem species properly called corundum. Now, corundum is not a word you would often hear while talking shop with socialites at parties, but within this gem species rests two of the most famous gem varieties in the world of colored gemstones- ruby and sapphire.



Ruby is actually red corundum, drawing its color from the presence of a trace element called Chromium. A few parts-per-million is enough to interact with the gemstone's chemistry to produce the red color widely coveted in the fine jewelry trade. Meanwhile, trace elements like iron and titanium can be responsible for producing a violetish-blue color, which results in the corundum specimen being designated to the blue sapphire variety.

Ruby and sapphire have very similar chemistry, with minuscule differences in the trace elements that create their differences in color. Sapphire though, is not always blue. While its bluish variety is indeed the most popular, sapphires can also come yellow, pink, green, purple, black, colorless and many other hues of the rainbow. Some of these hues may commonly occur in higher saturations than others. For example, violet-purple and green colored sapphires can appear grayish or muted in intensity, at least when compared to other gemstones of similar color (such as amethyst or emerald). All color of sapphire other than blue are grouped up and called 'fancy colored sapphires'.



The global gem market for sapphires is very diverse today. The biggest or most popular demand surges usually target blue sapphires, Padparadscha sapphires (pinkish-orange) and pink sapphires. Vivid yellowish sapphires are also commonly used, especially in seasonal tandem with the trendy color palettes governed by the fashion industry. Colorless sapphires (especially the lab-grown or synthetic versions) are sometimes utilised as diamond imitations as well, although their dispersion and brilliance are noticeably different from those of diamond.

Many sapphire colors are also produced by heating, or other more complicated enhancement procedures- like diffusing beryllium as a coloring agent into the stone's crystal lattice.

Also do keep in mind that synthetic corundum (lab-grown ruby and lab-grown sapphire) is a very common sight in today's jewelry marketplace. The flame-fusion process of creating man-made sapphire / synthetic sapphire is very widespread across many international manufacturers. Synthetic product can be created and sold at very low prices, as the creation technology (pioneered in the late 1800's) has grown accessible and affordable for many mid-scale entrepreneurs to get into.



Other similar creation methods, like the Czochralski process of growing crystal, are also being used today- not solely just for the jewelry industry, but also for military and industrial purposes as well. This is mainly due to corundum's high hardness (9) and general durability, as well as some of its other properties.

Many connoisseurs in the jewellery trade are familiar with the annual auction events held internationally. From Geneva to New York, greatly anticipated events led by the duopoly of Christie's and Sotheby's auction houses, have shown us some of the world's most tantalising jewellery from human history's most well known brands and designers.




Photography: Sotheby's Auction House, Plume necklace by Jean Schlumberger (Tiffany & Co.)

One particular storyteller we often like watching (just for his charismatic narration of significant pieces) is Frank Everett, who spotlights his own section called Frank's Files, on Sotheby's online platform. Here's an episode link where he timelessly describes a couple of novelty pieces from the collections of Barbara Sinatra (wife of Frank Sinatra) and Happy Rockefeller.



Some of the oldest jewellery design houses in the western world are often featured on his segments, including pieces by Cartier, Van Cleef & Arpels and Tiffany & Co. Both diamonds and rare coloured stones are often incorporated within the same piece, creating a mysterious allure unbound by a single hue or theme. Rubies, emeralds and sapphires are among the world's highest priced gemstones, and they're often found in the collections of society's most well regarded socialites and personalities.

The “Big Three” as they’re often called, constitute the vast majority of colored gemstone sales across most international markets. Rubies are traditionally the most expensive among them, given similar quality levels, however in the U.S. sapphire is more frequently purchased by end-consumers.

Depending on your familiarity with gemstones and gemology, you might find it surprising to know that rubies and sapphires are very similar to each other on an atomic level. Both are composed of crystalline aluminum oxide, but are colored by different trace elements. Chromium is responsible for ruby’s vibrant reds, while iron and titanium cause the violetish blue hues of sapphire.



Identification of a gemstone species involves taking note of different gemological traits. When checking rubies for example, our gemologists here at Gemcamp factor in tests that determine properties like optic character, growth structures, birefringence, refractive index and many others. Each gemstone species has its own unique and definable values that allow gemologists to separate it from another similar looking species. Red spinel for example can look identically similar to ruby by just the naked eye, however its crystal structure is actually more symmetrical on an atomic level compared to ruby’s. This can be observed using a polariscope, giving our gemologists information that they can use to scientifically pinpoint a gemstone’s proper identity.

Emeralds are composed of different elements altogether, they are beryllium cyclosilicates. Here at the laboratory, we also look for clues and indicators of identity under the microscope. Mineral inclusions such as pyrite can help us separate natural emerald from man-made emerald- which can be created today using a variety of proprietary methods. Chatham and Tairus are two companies abroad who have pioneered the development of artificial gem growth. They regularly produce man-made emeralds among many other gem species.



Be careful when you’re looking to authenticate a gemstone. Know that two gems can overlap in both clarity and color. Sometimes more in-depth knowledge is required before you can properly separate man-made gemstones from their natural counterparts. Awareness of the different types of inclusions and their significance also helps.

Our laboratory also makes use of advanced instruments for tasks that go beyond microscopy or standard gemological tests. We use spectrometry based instruments for the detection and separation of natural diamonds against lab-grown (man-made) diamonds, which are also composed of pure carbon, with identical properties like hardness, luster and brilliance.

What some people don't know, is that rubies and sapphires actually belong to the same gem species called corundum. Corundum is basically aluminium oxide that has crystallised in the trigonal crystal lattice system. It's pretty hard at a 9 on the Moh's scale, and at its most basic composition- is actually colorless. What makes rubies red and sapphires blue though?

Rubies get their red color from the presence of a trace element called Chromium. The percentage of chromium is very small, just a few parts per million actually, but this interacts with light and the surrounding atoms to produce various degrees of red and pink in corundum. Pink sapphire is also often primarily colored by chromium.

Sapphire on the other hand, usually refers to blue sapphire when used as a standalone term. Blue sapphire mostly gets its color from the presence of iron and titanium. Despite this, some people don't know that there are actually many different colors of sapphire- such as green, pink, purple, and orange. These are often called 'fancy sapphires' or are preceded by their respective color hues.



Corundum represents one of the most commonly used colored gemstones in the jewelry trade today. Rubies are traditionally the most expensive colored gemstone actually. Sometimes though there is debate over where the line holds clear in the definition between rubies and pink sapphires, as the only difference is in the strength and presence of the red color component. If a stone's color is too light, traders usually term it as pink sapphire instead of ruby.

Rubies belong to the gem species known as corundum, which is the trigonal form of crystalized aluminium oxide. Other members of this species include blue sapphire and fancy-colored sapphire. Natural ruby can be very rare, especially in its top color qualities. In the late 1800's however, man-made ruby started to emerge as a French Chemist named August Verneuil began the flame-fusion method of synthesizing corundum. Today experienced gemologists are able to tell the difference between flame fusion 'man-made' rubies and natural earth-mined rubies through microscopic observation. The value difference between the two is incredibly high, as synthetic rubies can even be purchased for a few dollars per-carat at wholesale.

The Rose of Mozambique (Photography Credit to Gemfields) reminds us of a lot of high-quality material that historically came from Burma or Myanmar's Mogok region. Despite that locality's fame, fine rubies are not limited to a certain country or specific source, and so it's wonderful to hear about Mozambique producing such a beautifully vivid gemstone from its soil.



Always be sure that your ruby stone is a natural product of the earth, and not a man-made version. There's nothing wrong with the latter, but you want to be sure of what you have, so that you know the proper standard by which it is valued and traded in today's jewelry industry. You wouldn't want to buy a beautiful "natural" gemstone for thousands of dollars only to figure out it could be easily grown in a factory right?

If you've been keeping up-to-date with the trend of gemstone treatment, you'll most likely be familiar with the treatment of fracture-filling. This is usually performed to enhance a stone's apparent clarity by concealing its fractures with a filling material with visual properties closer to that of the host gemstone's.



For many lower-quality, nearly opaque rubies, treaters have discovered a technique that basically pushes melted glass deep into the stone's heavily included interior, sometimes creating ratios up to 50:50 in terms of ruby versus glass material. The resulting gemstone is much more clearer and more marketable, so some people end up buying these stones overestimating their actual value.

Glass-filled or glass-composite stones do not look like synthetic stones to most people, at least through viewing by the naked eye. Their many cracks and crevices lend to the feeling of authenticity. Customers are more weary of stones that are perfectly clear and transparent. Many are less suspecting of these types of materials.

There is much debate on the nomenclature used for these types of products. On the one hand, the base material is indeed natural corundum, but the starting material is also so poor in quality that it would never have made it into the jewelry industry on its own merits. Some stones are filled with so much glass that people wonder if they should be called "composite-rubies" or "composite-gemstones" which is what some laboratories label them as.



While one might refer to them as 'real' due to the fact that the main stone is still natural corundum, the question you should be asking, is how should you see the value of such a product. The price for a majority glass-filled rubies is comparable to that of a flame fusion synthetic stone, sometimes higher or lower depending on the quality. The price for a high quality, untreated or heated-only natural ruby on the other hand, can be many times more expensive, reaching tens of thousands of dollars in range.

Note also that while the glass does improve the ruby's appearance drastically, it is much softer than the host gem, and because of its unique composition, poses a durability issue with regards to most cleaning methods used today. Many types of jewelry cleaners that are routinely used in the re-setting or repair of jewelry can eat away at the glass, causing it to degrade even after a few minutes.



The glass material is usually soft, as many treaters use a type of lead-glass, in order to match the refractive index of ruby (to better conceal the fractures). A material like this, can be easily abraded, and hurt by high temperatures like those caused by steam cleaners. Some reports have even noted that ultrasonic cleaning can also damage the glass filling of these stones, so beware of the implications that come with buying them. They are very affordable if bought with proper disclosure, but affordability comes with complications. Always ask your jeweller if your ruby has been treated in any way.

If they say that a ruby has been heat treated, make sure that heat is the only enhancement done, as this is quite normal and acceptable in the trade. Heating with fracture-filling or chemical diffusion can drastically lower the stone's value, so it's good to be aware of what type of gem you're actually buying.

Most of you know picture a scintillating, vibrant blue stone when you hear the word "Sapphire", don't you? It's not always common knowledge that sapphire is actually very similar to ruby on the atomic level. They're both varieties of a mineral called corundum that are simply colored by slight traces of other elements.

Sapphires are actually not all blue- it's just that the blue variety became the most famous due to demand, treatment procedures and historical usage.




Many patrons of old used to associate blue sapphire with the traits of faithfulness, sincerity and truth. Royalty and clergy both admonished themselves with this precious gemstone for centuries. Blue sapphires became the ultimate standard for the vibrant saturations by which every other blue gemstone was compared against.



Britain's most beloved princess- Lady Diana Spencer was proposed to by Prince Charles using a pristine blue sapphire ring, which was passed on to their child Prince William when the time came for him to get married as well.

The most famous source for blue sapphire is the mountainous Kashmir region, where the best qualities were touted as 'Cornflower Blue' sapphires. This trade label became quite famous and is still used today to depict some of the finest sapphire color profiles. The Kashmir mines though did not last for more than a few decades. Quite short in comparison to the long-drawn production timelines of other sources like Australia and Sri Lanka.

Other varieties of corundum aside from blue sapphire and ruby, are all called 'fancy sapphire'. These can be pink, orange, yellow, green, purple, black, or even colorless. Another high end corundum variety is called Padparadscha sapphire- inspired by the pinkish orange colors of a certain lotus flower. This relatively new variant has taken the gem world by storm and can match the finest blue sapphire for value in top market tiers.


It's interesting to note that before the Roman empire, sapphire was not actually known. Many of the gem's iterations in scripts and ancient text actually refer to lapis lazuli, being described as 'the night sky spangled with stars, or spotted with gold'.

Others put an attachment between crystals and their zodiac signs, which are different for the western and eastern versions of the zodiac system. The interweaving of crystals into our culture seems to be derived from history's longstanding view of crystals and gems as symbols of importance.

One particular, and very often uniformly accepted association of gemstones to human culture- is the designation of birthstones. Here's a quick look at each month's assigned birthstone according to the general public:

January's Birthstone is Garnet, which is actually an entire mineral group that's made up of different species and varieties- all called garnet as well. Tsavorite, Demantoid and Rhodolite are all garnets that have slightly different properties due to deviances in their crystals.

February's Birthstone is Amethyst. Along with citrine, amethyst is one of the most popular varieties of the mineral known as quartz. There was a time long ago when amethyst was considered as precious and as valuable as ruby, sapphire and emerald. When the vast Brazilian mining sources turned up, the supply of amethyst skyrocketed and was able to meet worldwide demand. Because of this though, it's prices also became much more affordable for everyone.



March's Birthstone is Aquamarine. This is the stone of the ocean, whose name is literally derived from the sea. Aquamarine is the second most expensive variety of the gem species known as beryl, and is the most famously known light-blue colored gemstone in the world.

April's Birthstone is Diamond, which needs no introduction. Diamond is the hardest mineral on the planet. It symbolizes one's eternal commitment to a partner, and has grown to be the ultimate symbol for marriage in our contemporary society.

May's Birthstone is Emerald. The green variety of beryl is typically its most expensive type. Emerald is also considered one of the 'Big Three' colored stones that make up a huge portion of the jewelry industry. It's said that the best emerald source is Colombia, where the mines of Muzo and Chivor produce emeralds with intensely saturated viridian greens.

June's Birthstone is either Pearl or Alexandrite. There are four types of pearls used today in the jewelry trade: Akoya, South Sea, Tahitian and Freshwater. Any can be used as appropriate birthstone jewelry for June. Likewise, alexandrite is also a famously traded stone today, as the color-change variety of fine chrysoberyl.

July's Birthstone is Ruby, which was once referred to as ratnaraj or 'the king of all colored gemstones'. Ruby actually holds the most expensive price-per-carat of all gemstones apart from diamond. It's also been mentioned in bible passages four times, and has a distinct recognition in the history of many popular cultures and ethnicities.

August's Birthstone is Peridot, which is the most famous light green stone variety in the world, and the gem-quality version of the mineral known as olivine. Peridot specimens were even harvested from meteorites that fell from space.



September's Birthstone is Sapphire. The blue hues of sapphire may be the most famous, but sapphire actually comes in a rainbow of colors, including orange, yellow, pink, black and green. Ruby and sapphire actually have nearly the exact same chemical composition, differing mainly just by their trace-elements that cause their unique colors.

October's Birthstone is either Tourmaline or Opal. Tourmaline is also a mineral group, and one that boasts the greatest variety of colors out of any popularly traded gem today. Some tourmaline specimens can even have up to five colors in a single crystal (Liddicoatite). Opal on the other hand, is an amorphous gem that exhibits a beautifully dazzling phenomena called play-of-color.

November's Birthstone is either Topaz or Citrine. Both are famously known golden gemstones, although topaz can come in other colors as well. These two gems are very much associated with fortune and the attraction of prosperity.

December's Birthstone is either Tanzanite, Zircon or Turquoise. Each of these three stones exhibit different shades of blue, with tanzanite usually holding the most in terms of saturation and intensity. It is also the most expensive of the three.




Some say that the origins of adopting gemstones to symbolize one's birth month has its roots in biblical sources. In the book of Exodus, there is a mention of Aaron's breastplate, which was inlaid with twelve different gemstones to symbolize the twelve tribes of Israel during that period. The stones that were present included sapphire, emerald, topaz, carbuncle, sardius, agate, amethyst, ligure, onyx, beryl, jasper, and diamond.

Carrying one's birthstone, or wearing it on your person is said to bring benefits to him or her, especially during the month of their birth. While this is again, outside of the gemological realm, it is a part of jewelry market studies. People often use birthstone themes to create beautiful pieces that appeal to each individual by a specific personal attachment (the birthday).

Whether you believe in birthstones or not, it is quite curious to note that gemstones that have had significance back during the days of our ancestors, still hold a special place and meaning for us today, in modern society.

It's no secret that there are rivers and streams that carry down pebbles of precious gem material from the mountains, but for Wayne Messer; a native fishing guide of the Appalachian Mountains, gemstones were literally sitting beneath his boots.



In the 1990's the gemstone buff was walking along the gravel filled stream bed of an area in North Carolina, when suddenly he caught a glimpse of some corundum. Corundum is the mineral species that both rubies and sapphires belong to.

Messer would usually follow this geological trail of minerals and find a deposit where gem-quality rough sometimes existed. For this particular story, he had to dig 8 feet down according to news sources, in order to reach the natural treasure hidden in the soil.

To his surprise, Messer's find eventually became four massive star rubies that totaled to about 342 carats. These were all museum-quality pieces that were intrinsically priceless as specimens.



One of the rubies, now called the "Appalachian Star Ruby" is considered one of the very largest star rubies to have ever been discovered in the US. Weighing in at about 139.43 carats, it's even larger than the famously known Rosser Reeves Star Ruby, which is displayed at the Museum of Natural History (Smithsonian)



Others in the collection, are the 52.37 ct. Misty Star Ruby, the 64.17 ct. Promise Star Ruby and the 86.56 ct. Smokey Mountain Two Star Ruby. The Smokey Mountain exhibits the phenomenal quality of asterism both on its front and on its back angles.



Now, decades after the initial find, Messer's family now pursues the auctioning of these magnificent ruby specimens through Guernsey's in New York. Several notable appraisals have valued the gemstone close to a hundred million dollars.



The four-stone collection, as we've heard, will be sold together in order to preserve the original find by Wayne Messer.

Star rubies are currently among the most valuable phenomena-possessing gemstones traded today, along with others like cat's eye chrysoberyl, color-change alexandrite and star sapphire. Many of these are considered specialty gems, amassed passionately by collectors from many different countries and societies.

Both ruby and emerald are among the most popular colored gemstones widely traded in today's society. Both have an allure that deeply connects with buyers, through the vibrancy of their corresponding colors; a crimson red and a vermillion green. Many who collect gemstones have at least a few specimens of each in their prized jewelry boxes, but not all know of a stone that can change from fiery reds in the evening, to verdant greens in the morning.



Alexandrite is the color-changing variety of chrysoberyl. It's remarkable composition and structure allows it to display a fascinating phenomenon that merges the appeal of two different hues. The presence of light plays a big part in alexandrite's transformative elegance. Incandescent light- such as the warm orange glow of burning candles, can make alexandrite's color turn a fiery red. It is often called the evening ruby, a nickname that has stuck for several decades since its popularity took flight.



In the morning, or much more specifically, under the cooler glow of natural sunlight or fluorescent light, most alexandrite specimens display a fine green that possesses just a touch of blue. The best samples of the stone show a stark, contrast between their two hues, creating the dual appeal of having both a ruby and an emerald (although chemically speaking, these belong to entirely different species).



Very fine stones are sold at auction for tens of thousands of dollars, and connoisseurs who are familiar with its name, offer to pay quite the hefty fee for a beautiful alexandrite.

It's accepted knowledge though that, no matter how rare or fine the alexandrite specimen, even the best ones will not completely match the saturation and purity of either ruby's reds or emerald's greens. Though despite this, some stones come pretty close, displaying colors convincing enough to fool onlookers into thinking the stone was actually something else.



Chrysoberyl, the gem species housing alexandrite, is also famous for having a cat's eye variety. These stones display chatoyancy, where a thin, sharp band gracefully moves across a domed surface, created by multitudes of parallel needles. Sometimes, color-changing alexandrite can also be fashioned with a cat's eye, displaying two beautiful visual phenomena at the same time.

Man-made rubies and sapphires have been circulating around the jewelry trade since the 1800's. The manufacturing method created by Auguste Victor Louis Verneuil for synthesizing corundum is still used to this day due to its affordability and convenience. Here in the Philippines, the mentality of most people dictates that if a gemstone has been passed down from older generations, it's most likely a genuine and natural item. For rubies and sapphires though, beware that this assumption may lead to very costly mistakes, especially in dividing up inheritances.



Here at the laboratory, we have seen enough synthetic rubies and man-made sapphires from clients, to know that a large portion of the jewelry buying population still does not know the difference between natural VS synthetic VS imitation stones. Natural fine rubies for example, are often worth tens of thousands of dollars, however synthetic rubies (also beautiful) are grown using an artificial method and can cost anywhere from 5 to 20 dollars per piece. Synthetic rubies are also called man-made, cultured or laboratory grown rubies, and it's imperative that jewelry buyers find out beforehand whether their ruby or sapphire is natural or synthetic.



Imitation rubies on the other hand, are simply lookalikes. While synthetic stones possess the same chemical composition and structure as their natural counterparts, imitations do not at all. They merely show some resemblance to precious gemstone materials, and are often used in costume jewelry or for fraudulent purposes. Be sure to ask your gemologist about the authenticity of your gemstone. Don't get fooled by charismatic vendors who spin wild stories about how their rubies and sapphires were unearthed in some ancient mining deposit, use science to distinguish fact from fiction.

Gemcamp will be conducting workshops on gemology later in the year, so feel free to message us if you're interested in joining the updater's list for when details do arrive from our management. These details have yet to be finalized, but we're currently already getting people expressing their interest in reserving one of the limited slots per month for our class sessions.

Today, the presence of glass filled rubies is quite prominent within the local Philippine community. Within the past few months, several stones of this type have been brought to the Gemcamp laboratory office for checking, because their owners thought that their stones looked "too blurred" or too clouded. Rubies in general can be heavily filled with tiny inclusions, but the presence of filler-glass (sometimes high in lead content) making up almost 40-50% of the ruby mass should be something to look out for.



What are glass filled rubies? These were originally low-quality ruby rough, the kind that would usually not pass for a gemstone. People think of more innovative and ingenious ways to market new products everyday, and this is exactly what happened here. Someone discovered that under certain conditions of pressure and heat, liquid glass could be inserted into the many thin fractures occupying low-end rubies. This caused them to suddenly look "clear", more transparent, and even more saturated in color at times.

Some laboratories would label these rubies as 'manufactured products'. Others would term them as 'filled rubies' or 'hybrid rubies'. Depending on the source, these stones could contain very large percentages of lead glass. The amount itself could even be more than the amount of actual ruby making up the gemstone.

Glass filled rubies are very inexpensive gems that were originally too poor in quality for jewelry use. Treatment and glass-filling makes them more marketable and transparent, but also creates durability issues and concerns.

Beware though, there are many sellers who will market these stones simply as 'natural ruby' or 'heat treated ruby'. The value of the gemstones associated with these two trade terms does not equal the value of a glass-filled ruby. Glass filled rubies are very commercial in price, while rubies treated with heat-only, are usually mid-market or could even be considered high-market, costing up to thousands of dollars per carat.



Glass-filled rubies also lose their beauty over the span of several years. The softer glass sometimes abrades or breaks up from the stone, causing cloudiness to increase and transparency to decrease. Even cleaning these stones in some high-powered jewelry cleaners can damage the internal filler slowly by slowly. It's very important to know what kind of gemstone you have, so that you can treat it with proper care and cleaning.

The best thing to consider is safety. If you feel like your stone is not what it appears to be, or not what somebody tells you it is, have it checked by a third party. Many labs can distinguish between different kinds of ruby using gemological expertise and specific equipment. Our facility in Metro Manila can always help distinguish glass filled rubies from their more valuable counterparts.

Not as much people are familiar with red spinel, but almost the entire world knows about the majesty of ruby. Both of these gemstones can come in a brilliant scarlet red, reaching vivid saturation levels on a pure earth-mined and untreated condition. Of course, those would be the top qualities of these gem varieties, and thus would command a hefty price in the industry.

To those who have seen the rarer fine qualities of red spinel, you must already be familiar with its likeness to ruby. The general trade also prizes spinel for its brilliant colors and fine luster. Its beauty is the favorite of many gemstone connoisseurs around the globe- and up until the 19th century, a vast majority of the general public actually believed this red gemstone to be ruby itself.

The advent of gemology and a better understanding of crystals gave way to the separation between these two gem varieties (which also belong to different species). Here, we will take a quick look at some of their differences.

First of all, rubies are a variety of corundum. This gem species belongs to the trigonal crystal system, is doubly refractive and will show "doubling" under strong enough magnification.

Spinel is a another gem species altogether, which belongs to the cubic crystal system. It is singly refractive, and therefore will never show any kind of "doubling" under magnification.

Doubling refers to the visual "duplication" of back facets or inclusions when you look through the gemstone's interior, provided you are not looking down an optic axis direction.

A polariscope can help you separate ruby from red spinel simply by observing if your red stone "blinks" or not as you turn it full circle under crossed polars. Ruby will do this because it is an anisotropic stone (DR), while spinel will not.

Ruby's hardness as the mineral species corundum is also rated at a 9 on the Moh's scale, while spinel ranks at an 8. Both gems are very hard with optimum durability traits.

When mining for them, rubies are most commonly found as hexagonal tablet shapes, while spinels could resemble partial or whole octahedral shapes.




Their specific gravities are also different, with spinel ranging at 3.58 to 3.61 and ruby at 3.9 to 4.1.
Some people are able to heft this difference by bouncing gemstones on their palms, but the more accurate way to determine SG would be using a scale with a hydrostatic attachment. You could also use SG heavy liquids at your preference.

Natural, Untreated Rubies Will Always Command Higher Prices Compared to Spinels of Equivalent Color Intensity and Overall Quality.

Separating ruby and spinel can also be supported by using a refractometer. Spinel has an RI value of 1.719, and shows a singular value (therefore there is no birefringence observation). Ruby on the other hand, shows RI values of around 1.762 to 1.770. This simply means that if you view the refractometer's scale while turning a polarizing filter in front of the viewer, you will see that ruby's RI value will change upon a 90 degree rotation. This value will first be around 1.762, then change to 1.770 upon the turn.

Both red gemstones are extremely remarkable, and can show us specimens of undeniable beauty and earthly rarity. Many people will agree that while they can often look very similar, an untreated ruby will usually have a much higher price compared to a red spinel of its equivalent quality. This is true especially in the finest hierarchies of their color and clarity grades levels.