Editing Opal (section)

== Synthetic opal ==
[[File:Colloid lithography, artificial opal, polystyrene.jpg|thumb|Artificial opal (made by drying a monodisperse sub-micrometer polystyrene sphere [[sol (colloid)|sol]]) viewed by darkfield optical microscopy]]
Opals of all varieties have been synthesized experimentally and commercially. The discovery of the ordered sphere structure of precious opal led to its synthesis by Pierre Gilson in 1974.<ref name=Klein /> The resulting material is distinguishable from natural opal by its regularity; under magnification, the patches of color are seen to be arranged in a "lizard skin" or "chicken wire" pattern. Furthermore, synthetic opals do not [[fluorescence|fluoresce]] under [[ultraviolet]] light. Synthetics are also generally lower in density and are often highly porous.

Opals which have been created in a laboratory are often termed "lab-created opals", which, while classifiable as man-made and synthetic, are very different from their resin-based counterparts which are also considered man-made and synthetic. The term "synthetic" implies that a stone has been created to be chemically and structurally indistinguishable from a genuine one, and genuine opal contains no resins or polymers. The finest modern lab-created opals do not exhibit the lizard skin or columnar patterning of earlier lab-created varieties, and their patterns are non-directional. They can still be distinguished from genuine opals, however, by their lack of [[Inclusion (mineral)|inclusions]] and the absence of any surrounding non-opal [[Matrix (geology)|matrix]]. While many genuine opals are cut and polished without a matrix, the presence of irregularities in their play-of-color continues to mark them as distinct from even the best lab-created synthetics.

Other research in macroporous structures have yielded highly ordered materials that have similar optical properties to opals and have been used in cosmetics.<ref>{{cite web |url=http://www.license.umn.edu/Products/Highly-Ordered-Macroporous-Structures__99014.aspx |title=Macroporous Structures, Metal Oxides, Highly Ordered |website=Office for Technology Commercialization, Technology Marketing Site |publisher=University of Minnesota |date=25 June 2010 |access-date=8 October 2011 |url-status=live |archive-url=https://web.archive.org/web/20120324152153/http://www.license.umn.edu/Products/Highly-Ordered-Macroporous-Structures__99014.aspx |archive-date=24 March 2012 |df=dmy-all }}</ref> Synthetic opals are also deeply investigated in [[photonics]] for sensing and light management purposes.<ref>{{cite journal |last1=Lova |first1=Paola |last2=Congiu |first2=Simone |last3=Sparnacci |first3=Katia |last4=Angelini |first4=Angelo |last5=Boarino |first5=Luca |last6=Laus |first6=Michele |last7=Stasio |first7=Francesco Di |last8=Comoretto |first8=Davide |title=Core–shell silica–rhodamine B nanosphere for synthetic opals: from fluorescence spectral redistribution to sensing |journal=RSC Advances |date=8 April 2020 |volume=10 |issue=25 |pages=14958–14964 |doi=10.1039/D0RA02245D |pmid=35497145 |pmc=9052040 |bibcode=2020RSCAd..1014958L |issn=2046-2069|doi-access=free }}</ref><ref>{{cite journal |last1=Tétreault |first1=N. |last2=Míguez |first2=H. |last3=Ozin |first3=G. A. |title=Silicon Inverse Opal—A Platform for Photonic Bandgap Research |journal=Advanced Materials |date=2004 |volume=16 |issue=16 |pages=1471–1476 |doi=10.1002/adma.200400618 |bibcode=2004AdM....16.1471T |s2cid=137194866 |issn=1521-4095}}</ref>