Lapis lazuli
On the label: Lapis lazuli · Gemstone
What it is
A rock, not a mineral: lazurite with pyrite flecks and calcite. Mohs 5 to 5.5, porous, often dyed to deepen the blue.
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: Contact metamorphic rock containing lazurite (but in most cases is haüyne), pyrite and calcite, mainly. Q216798 →
In the research
2 PubMed papers mention it with jewelry, allergy, eyewear or UV; the three most recent:
- Analytical Raman spectroscopy in a forensic art context: the non-destructive discrimination of genuine and fake lapis lazuli · Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2014
- Multitechnique characterization of lapis lazuli for provenance study · Analytical and bioanalytical chemistry, 2009
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.