Frequently asked questions

• Is spinel related to ruby or sapphire?

  No. Spinel is its own mineral species, magnesium aluminum oxide in the cubic crystal system; ruby and sapphire are corundum, aluminum oxide in the trigonal system. The two form in the same marbles and gravels and chromium colors both red, so red spinel passed as ruby for centuries until 1783, when Romé de l'Isle separated them by their crystal angles. Spinel is a little softer, 7.5 to 8 against 9, and it is singly refractive where corundum is doubly refractive. In bead form red spinel reads slightly softer in saturation than ruby.
• Is spinel treated?

  Spinel reaches the bead market untreated as a rule. Most spinel rough does not respond to heat the way corundum does, so cutters work the natural color, and the black, red, pink and gray-to-blue spinel sold here is natural: the color on the strand is the color the rough was mined in.
• What jewelry does spinel work in?

  At a hardness of 7.5 to 8 with no cleavage, spinel is one of the more wear-tolerant colored stones in the bead range: bracelets, rings and daily-wear pieces that would chip softer material. Small faceted rounds and rondelles in 2mm and 3mm serve as spacer runs, multi-strand layering and accents beside larger feature stones. Black spinel reads as a sharp, mirror-finished neutral beside sterling, gold-fill and oxidized findings. Red and pink spinel sit with garnet, ruby, rhodolite and rose gold.
• How is black spinel different from black onyx?

  They are different materials. Black spinel is a natural, iron-rich spinel at a hardness of 7.5 to 8; black onyx is chalcedony, usually dyed to an even black, at 6.5 to 7. Spinel takes a sharper, more reflective polish, and faceted black spinel reads almost mirror-like, with crisp facet edges that hold up. Onyx polishes to a softer, slightly waxy black and its facets read less sharp. Spinel carries the light where black is meant to act as a gemstone; onyx suits larger smooth rounds and flat backgrounds.
• How is spinel cleaned and stored?

  Spinel is low-maintenance for a colored stone. With a hardness of 7.5 to 8, no cleavage and good toughness, it is stable to light and chemicals, and ultrasonic and steam cleaners are usually safe; warm water with mild soap and a soft brush handles routine cleaning. Long contact with chlorine, bleach and strong solvents dulls a polish over time on any stone. Spinel is stored apart from softer stones such as turquoise, opal and pearl, which it scratches in ordinary jewelry-box contact.