Iolite
On the label: Iolite · Gemstone
What it is
Blue-violet cordierite, Mohs 7 to 7.5, strongly pleochroic (different colors from different angles). Untreated.
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 the mineral cordierite. Q122998805 →
In the research
No PubMed papers mention this material with jewelry, allergy or eyewear; that is usual for findings and trade terms.
Pieces whose listing names it
1 on the siteMatched from the words in the supplier's listing; the full material line is on each product page.
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.