Spinel is a mineral compound and can come into existence due to various distinct combinations of elements, the most common being that of magnesium and aluminum oxide. It is found in an array of colors just like sapphires though the most popular is the red spinel.
Apart from red, spinel comes in a variety of colors such as pink, blue, green, yellow, and brown. The presence of trace element chromium is responsible for red, pink and orange colors whereas iron gives it green color.
Spinel scores 8 out of 10 on the Mohs scale of hardness, making it very durable for everyday jewelry. Spinel has been used in jewelry for a long time but it was mistaken for ruby till the advent of modern technology.
Spinel was not recognized till 18th century when it was discovered that the famous 170 carat Black Prince's Ruby- the centerpiece of the Imperial Crown of England – was in fact a red spinel! Later it turned out that many other pieces in the royal jewelry are spinels. This sparked a general interest towards this gemstone and gradually it gained prominence.
The low profile of this exceptional gemstone has helped its availability at attractive prices particularly among collectors and investors.
Spinel is one of the three birthstones for those born in the month of August; the others are peridot and sardonyx. It is also the gemstone for the 22nd wedding anniversary.
The color, clarity, and transparency of a spinel are the three key characteristics that determine its quality. The price of a spinel, like that of any other gemstone, is directly proportional to its quality. The carat weight of a spinel is also an important element in determining its price These factors are described in detail hereunder:
The color of a spinel is the most important quality criterion and it determines the price of the gemstone. The color should be well-distributed with a high saturation level and the stone must be transparent. The price of a spinel increases with the increase in color saturation to a point where it doesn’t become overtly dark or oversaturated. At that point its price drops significantly. A very light color spinel and extremely dark / opaque spinel will have almost the same price. AFG uses its own color grading system for various spinel color types:
| Red Spinel Color Intensity | |
|---|---|
| Vivid | Best color without being overly dark (70% to 90% saturation) |
| Deep | Slight oversaturation of color |
| Medium | Shade lighter than vivid (50% to 70% saturation) |
| Purplish | More purple than red in saturation (30% to 50% red) |
| Pinkish | More pinkish than red in saturation (30% to 50% red) |
| Blue Spinel Color Intensity | |
|---|---|
| Cobalt | Best color without being overly dark (70% to 90% saturation) |
| Vivid | Shade lighter than Cobalt (50% to 70% saturation) |
| Deep | Slight oversaturation of color |
| Medium | Shade lighter than Vivid (30% to 50% saturation) |
Unlike diamonds which are inspected under magnification and are evaluated according to a standard grading system, color gemstones do not have a standardized grading system and it is extremely rare to find a spinel with no eye-visible imperfections.
Clarity refers to the presence or absence of internal and external imperfections in a gemstone. Generally, spinel is a much clearer gemstone when compared to other gemstones and as such clear spinels are easy to find with jewelers of repute. In the wholesale trade, we evaluate the clarity of a spinel in the following manner.
Below are the clarity gradings for spinel we utilize and are commonly used by most of our jeweler customers:
| Grading | Description |
|---|---|
| Eye Clean | 100% clean to the eye, but not necessarily under magnification |
| Very Slightly Included | Very tiny inclusions are eye visible under close inspection or when tilting the gem |
| Slightly Included | Tiny inclusions are eye visible |
| Moderately Included | Inclusions are eye visible |
| Included | Significant inclusions are eye visible |
Transparency refers to the attribute of a gemstone to let the light pass through. The more light passes through the more transparent the stone. Everyone loves transparent gems because the colors appear vivid. The only problem with higher transparency is that the flaws in the gemstone are more visible as compared to less transparent stone.
The rough of a spinel is cut in a way to obtain the desired color saturation of the spinel since the price is primarily dependent on the color. Lighter material is cut deeper to allow the gem to hold more light and increase saturation, whereas darker material is cut shallower to allow more light to pass through the stone.
Cutting a gemstone requires a high degree of skill which is mastered with years of practice and patience.
Carat (ct) is the primary unit to measure the weight of a gemstone. One carat equals one-fifth of a gram or one gram has five carats. The deep or the shallow cut of a spinel will have a bearing on its apparent size thereby making it important to consider other measurements viz. length and width which are expressed in millimeters. A 7x5mm Oval can weigh 0.80cts or 1.5cts, depending on its depth and cutting style.
Spinels are mined in many different places around the world. Gemstones of varying quality can be found in all origins. The spinel’s origin might affect its value, especially in higher quality spinels. Even if they are mined from a rare and prestigious location, spinels that are low in quality, will not receive a significant premium.
Spinels from Myanmar carry a premium over spinels from other origins and they are the most sought after. The premium is directly dependent on the quality and size/weight of the gemstone. It is recommended that one should focus more on the quality of the spinel that one wants to buy rather than the origin.
In the gem industry at present, there is no known and accepted treatment or enhancement for spinel and as such all spinel must be labeled untreated and should be sold as such. Jewelers of repute do not endorse any treatment on spinel and therefore customers must avoid spinel treated in any manner.
Spinel is a fairly hard gemstone and doesn’t require much care. But here are a few things that you can do to keep your spinel jewelry looking new.
