Ruby
On the label: Ruby · Gemstone
What it is
Red corundum, the same mineral as sapphire, colored by chromium. Mohs 9. Heat treatment is routine; glass-filled rubies (lead glass in fractures) are much cheaper and must be described as such.
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: Variety of corundum, mineral, gemstone. Q43088 →
In the research
67 PubMed papers mention it with jewelry, allergy, eyewear or UV; the three most recent:
- Generalized Laser-Induced Erythema Under General Anesthesia in Infants: A Case Series · Lasers in surgery and medicine, 2026
- Subtype-Specific Response to Fractional-Mode Q-Switched Ruby Laser in Melasma: A Prospective Single-Blind Clinical Study Using Clinical and Noninvasive Imaging Assessments · Clinical, cosmetic and investigational dermatology, 2026
- Ultrasensitive Pressure-Responsive Upconversion Luminescence in Cs(2)NaBiCl(6):Yb(3+)/Mn(2+) Optical Manometry · Advanced materials (Deerfield Beach, Fla.), 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.