Editing Conch (section)

==Pearls==
[[File:- conch pearl.png|thumb|alt=A gem quality 1.95 carat conch pearl displaying gem flame patterning|upright=.8|A conch pearl displaying flame patterning.]]
Many kinds of molluscs can produce [[pearl]]s. Pearls from the queen conch, ''S. gigas'', are rare and have been collectors' items since Victorian times.<ref name="skira.net">{{cite book|year=2007|first=Hubert|last=Bari|isbn=978-8861300132|publisher=Skira|title=Pink Pearl: A Natural Treasure of the Caribbean|id= {{ASIN|8861300138|country=ca}}}}</ref> Conch pearls occur in a range of hues, including white, brown, and orange, with many intermediate shades, but pink is the colour most associated with the conch pearl, such that these pearls are sometimes referred to simply as "pink pearls".<ref name="skira.net"/> In some gemological texts, non-nacreous gastropod pearls used to be referred to as "calcareous concretions" because they were porcellaneous (shiny and ceramic-like in appearance), rather than nacreous (with a pearly luster). The [[Gemological Institute of America]] and [[World Jewellery Confederation]] now use the simple term "pearl"—or, where appropriate, the more-descriptive term "non-nacreous pearl"—for such items,<ref>[http://www.giathai.net/pdf/05-15-07%20CIBJO%20Pearl%20Blue%20Book%20-%202007.pdf CIBJO 'Pearl Book'] {{Webarchive|url=https://web.archive.org/web/20110723134443/http://www.giathai.net/pdf/05-15-07%20CIBJO%20Pearl%20Blue%20Book%20-%202007.pdf |date=2011-07-23 }}. ''Giathai.net''; [http://www.gia.edu/gemsandgemology/620/30177/this_weeks_news_details.cfm GIA ''Gems & Gemology'' magazine news archive] {{Webarchive|url=https://web.archive.org/web/20090113164547/http://www.gia.edu/gemsandgemology/620/30177/this_weeks_news_details.cfm |date=2009-01-13 }}. ''Gia.edu''.</ref> and, under Federal Trade Commission rules, various mollusk pearls may be referred to as "pearls" without qualification.<ref>{{Cite web|date=6 July 2023|title=16 CFR §23.19: Definitions of various pearls|url=https://www.ecfr.gov/current/title-16/chapter-I/subchapter-B/part-23/section-23.19|access-date=2023-02-08|website=Code of Federal Regulations| publisher=Federal Trade Commission|language=en}}</ref>

Although not nacreous, the surfaces of fine conch pearls have a unique appearance. The microstructure of conch pearls comprises partly aligned bundles of microcrystalline fibers that create a shimmering, slightly [[iridescence|iridescent]] effect known as flame structure. The effect is a form of [[chatoyancy]], caused by the interaction of light rays with the microcrystals in the pearl's surface, and it somewhat resembles ''[[Moire (fabric)|moiré]]'' silk.{{cn|date=January 2024}}