Spinelleja

Spinelleja is a Finnish term that translates to "spinels" in English. Spinels are a group of minerals composed of magnesium aluminum oxide, with the chemical formula MgAl₂O₄. They are found in a variety of colors, including red, blue, green, yellow, purple, and black, depending on the presence of trace elements. Red spinels are often mistaken for rubies due to their similar color and occurrence in the same geological environments. Blue spinels are sometimes called "ceylonite" or "pleonaste."

Spinels are known for their hardness, ranking 8 on the Mohs scale, making them durable gemstones suitable for jewelry. They are also used as abrasives and refractories due to their high melting point and chemical stability. Historically, spinels have been prized for their beauty and have adorned royal crowns and other significant artifacts. Notable examples include the Black Prince's Ruby, which is actually a large, uncut red spinel, and the Timur Ruby, a large red spinel with an engraved inscription.

The geological formation of spinels typically occurs in metamorphic rocks, such as marbles and gneisses, or in igneous rocks like basalts and kimberlites. They can also be found in alluvial deposits, having been eroded from their parent rocks. The gemological properties of spinels, including their brilliance, fire, and durability, make them attractive to collectors and jewelers alike. While historically often misidentified, modern gemological techniques allow for the accurate identification of spinels, further increasing their appreciation in the gemstone market.