The cat’s-eye phenomenon: a mathematical approach

This paper provides a mathematical basis for the well-known cat’s-eye effect appearing on chatoyant gemstones. After reminding the reader of the physical origin of this effect and the conditions for observing it, we introduce all required parameters and some reasonable assumptions in order to simpli...

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Main Authors: Gauthier, Jean-Pierre, Bui, Thanh Nhan, Fereire, Jacques
Format: Article
Language:English
Published: Académie des sciences 2025-02-01
Series:Comptes Rendus. Physique
Subjects:
Online Access:https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.231/
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author Gauthier, Jean-Pierre
Bui, Thanh Nhan
Fereire, Jacques
author_facet Gauthier, Jean-Pierre
Bui, Thanh Nhan
Fereire, Jacques
author_sort Gauthier, Jean-Pierre
collection DOAJ
description This paper provides a mathematical basis for the well-known cat’s-eye effect appearing on chatoyant gemstones. After reminding the reader of the physical origin of this effect and the conditions for observing it, we introduce all required parameters and some reasonable assumptions in order to simplify the calculations. In fact, we describe the motion of a point located at the apex of the cat’s-eye line in the “main” plane, defined by the directions of the source and the observer and perpendicular to the set of acicular inclusions responsible for the optical phenomenon. These calculations confirm the qualitative cat’s-eye behavior commonly observed in various situations, when the source or the observer moves around the cabochon or when the stone rotates under them.
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institution Kabale University
issn 1878-1535
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publishDate 2025-02-01
publisher Académie des sciences
record_format Article
series Comptes Rendus. Physique
spelling doaj-art-d81ff8a3307245b3b58a2a0e3808f4732025-02-07T13:54:45ZengAcadémie des sciencesComptes Rendus. Physique1878-15352025-02-0126G118119810.5802/crphys.23110.5802/crphys.231The cat’s-eye phenomenon: a mathematical approachGauthier, Jean-Pierre0Bui, Thanh Nhan1Fereire, Jacques2Centre de Recherches Gemmologiques, 2 rue de la Houssinière, 44322 Nantes, FranceRue du Compas 47/4, 1070 Bruxelles, BelgiumCentre de Recherches Gemmologiques, 2 rue de la Houssinière, 44322 Nantes, FranceThis paper provides a mathematical basis for the well-known cat’s-eye effect appearing on chatoyant gemstones. After reminding the reader of the physical origin of this effect and the conditions for observing it, we introduce all required parameters and some reasonable assumptions in order to simplify the calculations. In fact, we describe the motion of a point located at the apex of the cat’s-eye line in the “main” plane, defined by the directions of the source and the observer and perpendicular to the set of acicular inclusions responsible for the optical phenomenon. These calculations confirm the qualitative cat’s-eye behavior commonly observed in various situations, when the source or the observer moves around the cabochon or when the stone rotates under them.https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.231/ChatoyancyCat’s-eyeAsterismOptical phenomenonMathematical approach
spellingShingle Gauthier, Jean-Pierre
Bui, Thanh Nhan
Fereire, Jacques
The cat’s-eye phenomenon: a mathematical approach
Comptes Rendus. Physique
Chatoyancy
Cat’s-eye
Asterism
Optical phenomenon
Mathematical approach
title The cat’s-eye phenomenon: a mathematical approach
title_full The cat’s-eye phenomenon: a mathematical approach
title_fullStr The cat’s-eye phenomenon: a mathematical approach
title_full_unstemmed The cat’s-eye phenomenon: a mathematical approach
title_short The cat’s-eye phenomenon: a mathematical approach
title_sort cat s eye phenomenon a mathematical approach
topic Chatoyancy
Cat’s-eye
Asterism
Optical phenomenon
Mathematical approach
url https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.231/
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