Spinel
On the label: Spinel · Gemstone
What it is
A magnesium aluminum oxide in red, pink, blue and black; Mohs 8, rarely treated, and the stone many historic 'rubies' turned out to be. Black spinel is the common inexpensive form.
Gemstones: Natural gemstones, as mined and cut. Hardness (Mohs scale) says what scratches what; treatment (heat, oil, dye) must be disclosed under FTC rules.
Wikidata: Oxide mineral. Q191310 →
In the research
72 PubMed papers mention it with jewelry, allergy, eyewear or UV; the three most recent:
- First-Principles Design of Cubic Spinel ZnIn(2)S(4) With Enhanced Carrier Transport, Optical Response, and Mechanical Stability for Photocatalytic and Optoelectronic Applications · ChemistryOpen, 2026
- Analytical First Principles Investigation of rare earth spinel chalcogenides BaGd(2)X(4) (X = S, Se) to explore the varying DFT potentials impacts on mechanical, optoelectronic, th · Journal of molecular graphics & modelling, 2026
- High-Purity Narrow-Band Green Light KAl(11)O(17): Eu(2+), Mn(2+) Phosphor Prepared Based on Energy Transfer Effect · Journal of fluorescence, 2026
A paper is a paper, not a verdict: titles are listed so you can read them, and a study on one fabric or one filter says little about the piece in your hand.
Other gemstones
Clasp & Lens describes materials from the public record and does not appraise, grade or test pieces; what a listing states is the supplier's statement. If a piece causes a rash, take it off; a reaction that spreads or blisters is a doctor's question, and sunglasses are no substitute for impact-rated eye protection where that is required.