Sapphire
On the label: Sapphire · Gemstone · a rule or standard applies
What it is
Corundum (aluminum oxide) in any color but red; blue is classic. Mohs 9, so suited to daily rings. Most sapphires are heat-treated, which the FTC requires sellers to disclose; untreated stones cost more.
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: Gem variety of corundum. Q127583 →
In the research
542 PubMed papers mention it with jewelry, allergy, eyewear or UV; the three most recent:
- Design principle: a broadband achromatic metalens · Applied optics, 2026
- 10-fs-level laser-to-RF timing jitter of a directly diode-pumped Ti:sapphire oscillator · Optics express, 2026
- 10-W-scale Kerr-lens mode-locked Ti:sapphire laser · Optics letters, 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.
Pieces whose listing names it
2 on the siteMatched from the words in the supplier's listing; the full material line is on each product page.
Made in the USA
Made in the USA
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.