SPINEL COLOR CHART

What's Synthetic Spinel?

Although not as widely used today as #Synthetic Corundum#, #synthetic Spinel# is still one of the most common man-made gem materials, particularly blue synthetic Spinel. It appears frequently in class rings and costume jewelry. Blue, green and other colors of synthetic Spinel are mostly manufactured using the inexpensive flame-fusion method by which the Spinel develops around an elongated boule. These flame-fusion Spinels can be distinguished from natural Spinels by a slightly elevated refractive index due to a chemical variation involving higher aluminum content.

Blue synthetic Spinels of the flame-fusion type are typically colored only by cobalt. No iron is added, and therefore they are diamagnetic, another property that distinguishes blue flame-fusion Spinels from blue natural Spinels. When viewed under the Chelsea filter and also under long wave UV light, the light blue and medium blue gems pictured below left and center show a pale pink reaction due to low cobalt content, while the dark blue gem on the right appears bright red due to much higher cobalt content. None of the synthetic Spinels shown below contain enough cobalt to cause magnetic attraction.

Blue Spinel gemstones manufactured by the slower and more costly flux-grown method have a vivid blue color due to high cobalt content. They are generally small in size, faceted from small synthetic crystals that are shaped like natural octahedral Spinel crystals, as opposed to the large rounded boule shapes of flame-fusion Spinels. Because the major chemistry is the same as natural Spinel, the refractive index range is also the same. While the common flame-fusion synthetic blue Spinels are almost always diamagnetic, flux-grown blue Spinels are weakly magnetic due to their higher cobalt content. This is the only gem material of any kind that we have found that shows magnetic attraction entirely as a result of cobalt. No iron or manganese can be detected.