Chalcedony
On the label: Chalcedony · Gemstone
What it is
Microcrystalline quartz in soft blues and greys; Mohs 6.5 to 7; often dyed.
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: Microcrystalline varieties of silica, may contain moganite as well. Q170448 →
In the research
2 PubMed papers mention it with jewelry, allergy, eyewear or UV; the three most recent:
- Color formation and illumination-dependent color variation of chrysoprase revealed by Kubelka-Munk optical analysis · Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2027
- [The Gemological Characteristics of One Kind Turquoise Imitation] · Guang pu xue yu guang pu fen xi = Guang pu, 2016
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
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.