how rare is the gemstone black spinel?

Question

I bought a black spinel 1.31ct. It is beautiful! Reading about it on the internet I found it is rare, However most stones are huge and you could not put them into a ring, the smaller stones are more expensive. Is it really more rare than a black diamond? Mine is transparent, all natural, black spinel requires no treatment other than polishing

Answer 1

Spinel (MgAl2O4) is a much maligned gem mineral that is often thought of as a corundum simulant because in red and blue varieties it can closely resemble ruby or sapphire. It is, however, an outstanding gem material in its own right; it is hard (8), possesses an intermediate to high R.I., shows good dispersion, and is available in a wide variety of colors. Many of the worlds most famous large "rubies" are, in fact, red spinel (e.g. Black Princes' Ruby and Timur Ruby, both in British Crown Jewels). Such stones were once referred to as Balas Ruby, a term that is not used today but is synonymous with red spinel. The confusion is well-founded; the finest red spinels come from the same gem gravel deposits in Myanmar that are renowned for "Burma" ruby, and both share somewhat similar optical and physical properties.
Spinel, like garnet and tourmaline, is a mineral name that refers to a group of minerals all having the same crystal structure. Members within the group differ by containing varying amounts of Fe, Cr, Zn, Mn and Ni that substitute for Mg and Al in the crystal lattice. Probably the most familiar minerals that have the spinel crystal structure are the ore minerals magnetite (Fe2+Fe3+2O4) and chromite (Fe2+Cr2O4), neither of which is a gem material. Gem spinel is usually quite close in composition to Mg, Al spinel but contains small amounts of Fe, Zn, and Cr that act as chromophores and account for the wide range of possible colors. Red and pink spinel is colored by trace quantities of Cr; blue, violet, orange and green by Fe. Zn, Cr, and Co (rare) are also present in some blue, violet and purple stones

Prices for 3-5 carat or stones of top quality where in the following ranges: These are old prices and may not be current.

Blue - $100-300/ct; no gray or other overtone.
Red - $500-$1500/ct.; no brown or gray overtone; should resemble fine ruby.
Pink - $100-$600/ct
Lavender - $50-$350/ct

Freedom From Inclusions
Ideally a spinel should allow the free transmission of light throughout its body without any hindrance - quite literally, the ideal is "crystal clear". However, as with all gems, reality tempers our expectations with a few of nature's fingerprints.
The GIA divides all colored gems into three categories for the purposes of clarity grading, based upon their habitual tendencies to exhibit inclusions:
TYPE I Often virtually inclusion-free
TYPE II Usually slightly included
TYPE III Almost always included
Spinel is categorized as a Type II colored gem, meaning specimens are frequently slightly included and fall just short of being thought of as a habitually flawless gem type. While ruby and red spinel may share the same broad, generalist Type II category, experience teaches us that in reality red spinel is habitually cleaner.

Answer 2

Black Spinel

Answer 3

O.K. you have had two very good descriptions of spinel, neither of which answered your question.
Black spinel is not at all rare, it is the fine coloured clean stones that have rarity value. The black material requires cutting and polishing just as any gemstone but being black it does not transmit light and so the proportions of the back of the stone are unimportant as it is only reflected light from the visible facets that can be seen. A black stone has no problem with internal flaws as these cannot be seen and so poor quality crystals can be cut into gems. As with all gemstones small stones are far more common than large ones and as such are much cheaper. I have the horrible feeling that you have been listening to too much sales talk without doing any research to counterbalance it with.
You describe your stone as transparent which I find hard to understand as you also stated it is black and the two things do not go together.
The great thing about stones is that you find them attractive and that they give you pleasure - these two things can never have a price put on them so go on enjoying your gem.

Answer 4

Spinel Stone

Answer 5

Availability :
Spinel is relatively unheard of to the common consumer and has not been marketed by any major gem companies. Black Spinel is only found in a few locations in the world, and because of its rarity, if the demand were to rise, supply would not be abundant enough to keep up with it.

Sources :
Black Spinel is mined mainly in Thailand (Boi Ploi, Kanchanaburi), where it is known as “Nin”. There are also known deposits in Africa, Myanmar (Burma), and Sri Lanka.

Evaluation :
Black Spinels are rated at 8 on Moh's Scale of Hardness and are a durable stone that lacks cleavage, making it suitable for all jewelry purposes. Black Spinel looks elegant when set with a quality piece of gold or silver jewelry because of the striking contrast. Black Spinel is the opaque jet-black variety of the Spinel family and it lacks the metallic luster of other popular black gemstones. Spinels are a favorite amongst gem connoisseurs and gem collectors alike, and makes a beautiful, durable stone for all jewelry purposes.

Common Cuts :
Spinel is a durable stone that lacks cleavage and for this reason it is suitable for all jewelry purposes. It is most often found in oval, round, and cushion cuts, and due to its rarity Black Spinel cannot currently be found in calibrated sizes.

Routine Enhancements :
here are no known enhancements for Black Spinel.

Care & Cleaning :
Spinel is a very durable stone that lacks cleavage making it difficult to chip and scratch. Steam and ultrasonic cleaners are generally safe but they should be used with caution. Avoid household chemicals and prolonged exposure to excessive heat that can alter the color or damage the stone. Spinel can also be cleaned in warm soapy water with a soft brush. Always store your Spinel jewelry in a fabric-lined box away from other jewelry items in order to avoid scratching.

Answer 6

The third answer is a very good one but I would add our experience as a miner of this gem.

I would expect that your black spinel is opaque, not transparent and should not have cost a lot of money. We operate a sapphire mine and cut/sell black spinel. However, while our resource does produce a good amount of black spinel, we produce none in other colours. The prices quoted in the first answer are very much higher than what would normally be asked for black spinel.

Other mines nearby to us only produce very small amounts of black spinel. In our experience, it is rare but unappreciated - mines that could produce this gem sometimes do not bother to separate it from the unusable portion of their mine production.

Rarer than black diamond ? Not sure, black diamond is usually created by irradiation so in my opinion, it is not really a good comparison. It is sometimes not easy to source this gem in a range of sizes/shapes but smaller stones should not be very expensive at all. Sometimes not easy to find very small sizes in calibrated sizes (suitable for accent stones) as some sellers like to concentrate on the very large sizes.

Understandably, there is less market demand for black gems compared to the brighter, more attractive colours. Although much easier to handle than most transparent gems, there are differences in quality. Stones that come from other resources where large sizes are more common sometimes do have internal flaws which can cause difficulties when cutting and polishing.

I am glad you like your black spinel - it is a great gemstone for someone looking for a pure and natural black stone.

Answer 7

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It is good as long as you bought it as a spinel, and not as a ruby or sapphire. Spinels are nice gems in their own right, but are often passed off as something else, because of their color. See description following. The world's most famous two spinels are part of the British Crown Jewels, but these beautiful red gems are traveling under an assumed name. This little-known gem is so similar to ruby that many of the great rubies of history are spinels. Case in point: the Black Prince's Ruby on the British Imperial State Crown is a magnificent 170-carat red spinel. The Timur Ruby, a 352-carat red spinel now owned by Queen Elizabeth, has the names of some of the Mogul emperors who previously owned it engraved on its face. They also thought that this magnificent red gem was ruby. It's not surprising that ruby and spinel were long confused. Both are mined in the gem gravels of Burma and Sri Lanka. They have similar hardness and durability, vivid color, and brilliance. Ironically red spinels, often referred to in ancient texts as balas rubies , are actually more rare than ruby but, unlike ruby, they can sometimes be found in very large sizes. Balas , or Balascia , refers to Badakshan in northern Afghanistan, an active gem-producing region during the Middle Ages whose big and beautiful red to pink spinels were considered the best rubies of their time. So the spectacular “rubies” owned by Tamerlane, the Mongol conqueror, Henry VIII of England, and Peter the Great of Russia are all spinels. Now treasured for its own sake, spinel is a favorite of gem dealers and gem collectors due to its brilliance, hardness and wide range of spectacular colors. In addition to beautiful rich reds, spinel can be found in a range of beautiful pastel shades of pink and purple. Of particular interest is a vivid hot pink with a tinge of orange that is mined in Burma that is one of the most spectacular gemstone colors in any gem species. Spinel also comes in beautiful blues, but these are extremely rare. In addition to Burma, now known as Myanmar, and Sri Lanka, spinel is mined in Tanzania and Tadjikstan, part of the former Soviet Union. Fine spinels are often set in handcrafted one-of-a-kind jewelry by custom goldsmiths, since these gems are too rare to be cut in standardized sizes. Its beauty, brilliance and lush saturated color make it one of the gem world's best bargains. Spinel is a durable gemstone that is perfect for all jewelry uses, with a hardness of 8. It is most often faceted in oval, round, or cushion shapes. Clean with mild dish soap: use a toothbrush to scrub behind the stone where dust can collect.

Answer 8

I have two sources for information: The 22nd edition of the manual of Mineral Science pg. 388, 389:

Spinel is a common high-temperature mineral occurring in contact metamorphosed limestone and metamorphic rocks poor in SiO2. It occurs also as an accessory mineral in many dark igneous rocks. In contact metamorphic rocks it is associated with phlogopite, pyrrhotite, chondrodite, and graphite. Found frequently as rolled pebbles in stream sands, where it has been preserved because of its resistant physical and chemical properties.


Field Guide to North American Rocks and Minerals pg 416

Color: Red, green, blue, brown, black.

Environment: Spinel forms in plutonic and metamorphic rocks. It is associated with olivine and hornblende in gabbro of plutonic rocks, and with pargasite, phlogopite, and chondrodite in hornfels and marbles of metamorphic rocks.

Occurrence: Perhaps the finest spinel comes from localities in Ceylon and Burma. Fine sharp crystals have been found in calcite veins in Ross Township, Renfrew Co., Ontario, and in St. Lawrence Co., New York. Sharp crystals, some of them measuring more than 12.5 cm (5”) on the edge, have come from the Sterling Hill Mine at Ogdensburg, Sussex Co., New Jersey. Pink, green, black and lavender crystals have come from a body of metamorphic rock in E Fresno Co., California.

Spinel occurs in many colors: red, pink, rose, and yellow to orange spinel is called rubicelle; purple spinel is called almandine spinel, and blue to dark green to black spinel is called pleonast.

Spinel has a crystal shape that is Isometric, usually in octahedral crystals or in twinned octahedrons. The color variations are due to the wide range of chemical substitutions that can be made within the crystal structure. Many of the minerals that are associated with spinel are dark in color. My sources express no extraordinary rareity to any particular color.

Answer 9

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