Spinel
Spinel
Spinel is a fascinating gemstone, long confused with ruby or sapphire before modern gemology clearly distinguished these minerals. Scientifically, it is a magnesium aluminum oxide (MgAl₂O₄), with a cubic crystal structure that often gives it a beautiful natural symmetry. Its hardness is around 8 on the Mohs scale, making it a fairly robust gem for jewelry. Unlike some gemstones, spinel is generally minimally treated: its color is often naturally attractive, which adds to its appeal.
Its color variations are particularly rich: red, pink, purple, blue, gray, black, and even orange. These hues come from trace elements such as chromium (often responsible for reds), iron (which can darken or blue), or cobalt (responsible for certain very intense and rare blues). Spinel also has the advantage of being isotropic, meaning it does not exhibit pleochroism: its color remains stable regardless of the viewing angle, a highly valued characteristic when cutting. It is found in alluvial deposits and in certain metamorphic rocks, notably in renowned regions such as Myanmar (Burma), Sri Lanka, Vietnam, and Tanzania.
Some stones display characteristic inclusions that help confirm their natural origin and differentiate them from synthetic spinels. Historically, several famous "rubies" in royal crowns have turned out to be spinels, a testament to their resemblance and beauty. For care, gentle cleaning with warm soapy water and a cloth is sufficient, avoiding harsh impacts as with any gemstone. Between trace element chemistry, crystalline structure, and color palette, spinel is a stone as scientific as it is elegant, ideal for those who appreciate authentic and less "classic" gems.