How to identify real spinel?
Natural gem-quality spinel has been rapidly gaining popularity in recent years as a rare precious and “semi-precious” stone. A situation arises in the market of increasing demand in conditions of limited supply. In the world mineralogical community it is known under the English term “spinel”. The name of this mineral has Latin roots and comes from the term “spinella”, which means “thorn”. This is a direct indication of the crystal shape, octahedron and dodecahedron, in the form of which the mineral is formed in nature. Its properties as a precious stone are remarkable. Spinel has a strong glass luster, which makes it easy to polish and very beautiful to cut. Another excellent property is the high dispersion, which is 0,026. The hardness of the mineral is very high, about 8 on the Mohs scale, which is close to the values of beryl, topaz and slightly less than that of noble corundum, ruby and sapphire. Among the characteristics of this stone, the most important is color; red shades, including pink, and blue are especially valued. In addition, purity, quality of cut, weight and origin influence the cost. We will tell you more about how to choose this noble stone in this buyer’s guide, and in the second part of the guide we will summarize how much cut natural spinel costs.
Colors and types of spinel
The correct answer to the question: “What color is spinel?” is “almost any.” Her palette is incredibly diverse: pink, red, orange, blue, blue, purple, black. Sometimes there are colorless, yellow and green stones. The color of the mineral depends on the content of impurities of various elements in the structure. The bright red variety is considered the most valuable. Rare neon blue cobalt spinel is also highly prized; when cut, it rarely exceeds a couple of carats. Next, we will look at the features of each color type of spinel:
Red
The most valuable natural variety, often referred to in literature as “lal”. Its properties are such that, according to its external description, red spinel is extremely similar to a scarlet ruby. It is sometimes referred to as ruby or chrome spinel because the color comes from the presence of chromium in the structure. The red color can be of different saturations, from light to dark, almost black, sometimes the stone contains additional shades: orange, brown, purple. Being present in large quantities, they significantly reduce the cost of a sample, so pure red colors of medium and high saturation are most suitable for investment purposes. In the photo: a rich red specimen of natural red spinel Of particular interest lately has been the appearance on the market of single specimens of Jedi spinel; it seems to glow from within and is of Burmese origin. As a rule, the weight of specimens does not exceed 2 carats.
Pink
A worthy noble stone with a delicate and romantic pink hue, it is suitable for creating world-class women’s jewelry; surrounded by white diamonds, pink spinel is especially delightful. The most famous deposit is located in the Pamirs, Tajikistan. Pamir pink spinel is good due to its pure light pink hue, without additional tones. This is valuable because the color of such a spinel is close to the tone of a pink diamond: a little cool, not bright, but not pale either. Other deposits include Vietnam, Burma, Tanzania. Specimens from Tanzania (Mahenge) can reach a rich neon red-pink. An untrained eye will consider such a stone to be synthetic; it seems to glow from within. Avoid purple and orange shades, they will reduce the value of pink spinel.
Orange
Orange is a rather rare color for this mineral, and may have a red or yellow tint. When cut, it looks bright and juicy and goes well with the color of yellow gold. Orange and orange-red spinel are sometimes referred to by the commercial name “rubicell”. This look is not dark, sometimes it looks neon.
Blue
One of the most valuable varieties. If the coloration of the sample is caused by cobalt impurities, the commercial variety will be referred to as “cobalt” accordingly. Color – in shades of blue, from dark blue to bright neon. Sometimes it can be found under the term ganospinel, ganite. Often, blue spinel can have a grayish or purple tint, and even have a subtle color change effect depending on the type of lighting. Excessive density of blue is a price-reducing factor, so when choosing spinel we recommend avoiding dark samples.
Blue
This blue stone is a very attractive gemstone. It is not very common, a pure bright, sometimes neon sky color is incredibly good, extremely rare. It is usually associated with the Luk-Yen deposit in Vietnam. Due to its rarity, neon blue spinel of this origin is sought after by mineral and gem collectors.
Purple
The pleasant purple color of spinel, sometimes with a little pink or steel gray, looks elegant and delicate in jewelry. In light lilac and lavender specimens, the play of color on the edges – dispersion – is beautifully revealed.
Black and gray
Black spinel is an inexpensive, common semi-precious stone, generously used in silver jewelry, beads and costume jewelry. This variety is interesting because when cut it looks like a black diamond. It ranges from gray transparent to black opaque, however the highly polished black variety has an excellent shine. Pictured: steel spinels
Green
This green stone is little studied and rare. Its color varies from bright green to dark green, the color is often weakly saturated, slightly grayish. Being caused primarily by chlorine impurities, this species may be referred to as chlorospinel. Offers of truly attractive jewelry pieces are rare on the market.
White (colorless)
The rare white variety of this gem appears colorless, however, sometimes there may be a slight shade of pink, gray, or lavender, which can appear in different lighting. The structure of colorless spinel has no or minimal coloring impurities and is highly transparent. In the photo: colorless cushion-cut variety Like other colorless stones, for example, sapphires, beryls, topazes, danburites, when cut it resembles a diamond. However, due to different properties, lower dispersion and gloss values, it plays more modestly.
Cutting
Spinel has a strong glass luster, it takes polish well, and is very beautiful when cut. Also a big advantage is the high dispersion. It must be taken into account that in saturated red, pink and blue stones it practically does not appear and is revealed only in cut specimens of light, gray, light pink, bluish colors. The following cut shapes are popular: Much less often, individual specimens have the shape of a circle, marquise, trillion, or heart. The issue of selecting pairs and sets of three or more stones requires separate discussion. For more common types (gray, for example), with stones weighing up to 1,5-2 carats, it is relatively easy to make a selection. However, for rare red, pink, purple, blue spinels from 2 carats, selecting a good pair with the most similar characteristics is a real quest for a gemologist. Stones may vary in color, clarity, and cut, so to ensure a perfect match, the stones are recut. Despite the sometimes significant weight loss, the result is worth it, so pairs and sets of spinel have an additional markup of 10-20% and are more expensive.
Cleanliness
Only a small part of the mined raw materials in crystals and fragments is of jewelry quality and is suitable for cutting. The spinel gemstone must have high purity, a small amount of gas-liquid, mineral inclusions, small cracks that do not impair the appearance of the sample are acceptable. In the presence of large, noticeable inclusions and cracks, the value of spinel decreases.
How to distinguish real spinel from a fake
This is a pressing question, since there are a large number of imitations and fakes on the market today. Among artificial materials, these are primarily glass (the so-called jewelry pastes), glass ceramics, and cubic zirconia. Particular attention should be paid to the synthetic analogue – artificial aluminum-magnesium spinel, obtained in laboratory conditions. Thanks to the addition of coloring impurity elements during the synthesis process, scientists obtain a wide range of colors and shades: green, blue, red, pink, purple, colorless, etc. The most reliable way to distinguish a natural mineral from a counterfeit and synthetic analogue is in the laboratory, by its characteristic features using gemological methods and related equipment. All lots presented in the Gem Lovers catalog are carefully studied in advance by the company’s gemologists. The buyer can also order the production of a certificate or expert opinion from a reputable certification center. Among natural stones, minerals such as garnets (almandine, pyrope, rhodolite), tourmaline rubellite, zircon hyacinth, and fancy sapphires resemble natural red and pink spinel. Gems similar to blue and blue spinel: blue sapphire, Cambodian zircon, indigolite tourmaline. Go to part 2 of the buyer’s guide, in which we talk about the cost and give real prices per carat. 
Synthetic raw materials are widely used in jewelry; instead of natural spinel, you can buy a fake. Crystals and spectacular druses are grown using different technologies. Some examples of red are so good that they are sold at prestigious auctions under the guise of precious stones.
How spinel is counterfeited
Visually, high-quality synthetic crystals are identical to natural ones, so external characteristics will not help distinguish natural spinel from a fake. Only armed microscope and a certain set of knowledge, it is possible to determine the origin of a jewelry stone.
It’s easier to understand that this is a fake when the insert is an imitation:
- colored glass;
- triplets, doublets (natural stone + glass);
- cubic zirconia with similar optical properties.
A crystal grown in laboratory conditions is identical in appearance to natural crystal. Companies producing synthetic raw materials use expensive technologies borrowed from nature.
Colorless, greenish-yellow, light blue samples are grown from the melt:
- gas-flame Verneuil method;
- using Czochralski crucible technology.
Beautiful red gems, which are passed off as “royal Burmese” spinel, are crystallized from a solution in a melt using the flux method. In jewelry, colored spinel is widely used to imitate other minerals (Alexandrite, tourmaline, zircon, aquamarine, ruby). To obtain the desired color, chromophores (Cu, Co, Fe, Mn, Cr) are added to the mixture.
Natural spinel or fake: how to distinguish
Most often, fakes are purchased while traveling in South America and Asia: traders sell rings and earrings with spectacular composite inserts to tourists. Passed off as natural stone doublets, triplets, unjustifiably inflate the price.
The second common type of deception is rings, earrings, bracelets and necklaces with synthesized gems. True, such products are considered fake only in cases where the product description does not indicate insertion origin.
Refractive index
There are several diagnostic signs that help distinguish a fake. The first is the refractive index. For fine gem-quality spinel it is in the range of 1,712-1,716 and depends on the color.
For gems grown by the Verneuil method, this indicator is higher – 1,73, which makes diagnosis easier. Samples received flux method, you can’t tell by the refractive index, it’s like that of natural stones – 1,716.
Laboratory and natural crystals do not have birefringence
Internal microinclusions
The second diagnostic sign is internal microinclusions. They determine not only the origin, but also the deposit. Natural gems of Sri Lanka contain inclusion baddeleyite, titanite and zircon. Jewelry raw materials from Burma include olivine, apatite, dolomite and calcite.
The synthesized crystals have different inclusions; under a microscope you can see:
- gas bubbles;
- crucible material;
- unmelted starting material;
- flux.
Jewelry raw materials grown using the flux method are difficult to diagnose, and at home it is simply impossible. Only a professional can distinguish falsification. In any large city there are organizations that conduct gemological examinations and issue certificate compliance or expert opinion.
Jewelry quality stones are mined in Madagascar, in Vietnam Myanmar and Sri Lanka. Pure crystals have no visible defects. Inclusions can be examined through a magnifying glass or microscope. Their presence and specific shape confirm their natural origin.
From the video you can learn how to determine a spinel deposit by the shape of the inclusions:
