228 results
Search Results
202. Combined shock-wave synthesis of noble spinel and laves cubic phase.
- Author
-
Tsvigunov, A., Krasikov, A., and Khotin, V.
- Subjects
- *
SPINEL , *GEMS & precious stones , *ALUMINUM powder , *COPPER , *HIGH temperatures , *LAVES phases (Metallurgy) - Abstract
The paper described the shock-wave synthesis of high-pressure high-temperature mineral MgAl2O4 with the parameter a = 8.085(3) Å and the Laves phase MgCu2 with a = 7.076(2) Å from a mixture of MgO and aluminum powder placed into a copper insert inside a steel conservation ampoule. Spinel MgAl2O4 with a smaller lattice parameter a = 8.0798 Å has been formed in an aluminum insert cup. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
203. AMERICAN RENAISSANCE.
- Author
-
BROWN, JOE
- Subjects
- *
CLOCK & watch making , *LATHES , *GEMS & precious stones - Abstract
The article offers information on watchmaker Roland G. Murphy, who founded RGM Watches, and mentions how he works a 1913 Swiss lathe called a Rose Engine. Topics discussed include the education background of Murphy at Bowman Technical School in Lancaster, Pennsylvania, the use of synthetic gems by watchmakers for making watches, and the four cast-metal engine-turning machines used at RGM.
- Published
- 2017
204. Theory and modelling of diamond fracture from an atomic perspective.
- Author
-
Brenner, Donald W. and Shenderova, Olga A.
- Subjects
- *
DIAMONDS , *GEMS & precious stones , *FRACTURE mechanics , *CLASSICAL mechanics , *DEFORMATIONS (Mechanics) - Abstract
Discussed in this paper are several theoretical and computational approaches that have been used to better understand the fracture of both single-crystal and polycrystalline diamond at the atomic level. The studies, which include first principles calculations, analytic models and molecular simulations, have been chosen to illustrate the different ways in which this problem has been approached, the conclusions and their reliability that have been reached by these methods, and how these theory and modelling methods can be effectively used together. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
205. Visual Arts: Mesoamerica.
- Author
-
Klein, Cecelia F.
- Subjects
INDIGENOUS art ,ART materials ,HUMAN figure in art ,METALWORK ,GEMS & precious stones ,WEAVING ,INDIGENOUS peoples of Central America - Abstract
Focuses on the Mesoamerican visual arts. Art materials used to depict the beauty of the human body; Emergence of metalworking and precious stones during the Postclassic period; Methods used in weaving cloth.
- Published
- 2001
206. TURQUOISE with Fingerprint Pattern.
- Author
-
Allen, Tara and Cooper, Amy
- Subjects
- *
NECKLACES , *GEMS & precious stones - Abstract
The article discusses the examination of a turquoise bead necklace by the Gemological Institute of America (GIA)'s Carlsbad laboratory in California and adds the research paper "Gemstone enhancement and its detection in the 2000s" by researcher S.F. McClure and colleagues.
- Published
- 2013
- Full Text
- View/download PDF
207. Colours of the Ocean!
- Subjects
BEAD making ,BEADS ,ART materials ,LAPIS lazuli ,GEMS & precious stones - Abstract
The article evaluates beads for jewellery from beads manufacturer lush rocks including the Aqua Aura quartz beads, the faceted Chalcedony Briolettes and the tiny lapis lazuli beads.
- Published
- 2015
208. 7 The Inalienability of Jades in Mesoamerica.
- Author
-
Kovacevich, Brigitte
- Subjects
- *
JADE jewelry , *JADE art objects , *GEMS & precious stones , *JADE , *DURABILITY , *ESOTERICISM - Abstract
ABSTRACT The rarity of jade as well as its hardness, durability, and sacred color gave it a value incomparable to other materials in Mesoamerica. The labor investment of the crafter, the esoteric knowledge used to create the objects, and the identity of the possessor(s) all contributed to the legacy of jades as inalienable possessions. Jades were gifted, displayed, interred, and even destroyed in honor of the history, memory, prestige, and identity of the object and of the possessor, which were mutually constituted. Jades that were once thought to simply legitimate the elite prestige may have had nested social meanings, and the concept of inalienable possessions can help us to understand that complexity. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
209. Gems in nanoscience.
- Subjects
- *
OPTICAL diffraction , *LIGHT , *GEMS & precious stones , *NANOSCIENCE , *PLASMONS (Physics) , *OSCILLATING chemical reactions , *DIAGNOSTIC imaging , *SIGNAL detection - Abstract
In 1902 R M Wood published the paper ''On a remarkable case of uneven distribution of light in a diffraction grating spectrum'' [1]. As was true of so much of his work, interest in his observations took flight, inspiring extensive research into associated new optical phenomena. What is now known as Wood''s anomaly has been described as the result of excitations of oscillations in the conducting electron plasma, or ''plasmons''. These quasiparticles have become increasingly attractive to researchers, perhaps less for the dazzling colours they impart to glitzy gemstones over their potential to facilitate medical imaging, as well as integrated optics [2] and the transfer of information and energy at dimensions below the diffraction limit. Excitation of surface plasmons provides a means of enhancing optical near fields, thus empowering a range of signal detecting applications. A range of innovative techniques have been implemented to probe surface plasmon resonances. The evolution of plasmon resonance energy and mean free path as particle dimensions increase from nanostructures to bulk matter has been monitored through ellipsometry, thus providing an insight into the plasmon polariton coupling [3]. Electron energy loss experiments have also proved a valuable tool for mapping surface plasmons with a spatial resolution an order of magnitude better than can be achieved with scanning near-field optical microscopes [4]. The exploitation of surface plasmons is primed to aid advances in medical imaging, diagnosis and therapy. Researchers in the US have developed a protein-enabled strategy to fabricate quantum dot nanoarrays where an increase in surface-plasmon-enhanced fluorescence of up to a factor of 15 has been achieved [5]. Understanding and dexterity in manipulating these enhancements has reached a high level of sophistication, and researchers in London have demonstrated the ability to increase the fluorescence enhancement by a factor of 4 and the decay rate by a factor of almost 30 by tuning the localised surface plasmon resonance of silver particle arrays to the emission wavelength of a locally situated fluorophore [6]. In the US and Belarus researchers have collaborated to investigate the potential of plasmonic nanobubbles, generated by laser activated nanoparticles, for combined diagnostics, therapy, and therapy guidance. Such nanobubbles can be optically tracked in the body, and their rapid expansion and collapse provides a localised mechanical impact on cells that can disrupt the cell membrane [7]. Surface plasmon polaritons at nanostructures allow highly local control of light, which has a range of uses in electronic devices. Photovoltaics researchers in the US and the Netherlands have demonstrated enhanced short circuit current densities compared to cells having flat or randomly textured back contacts using nanostructured plasmonic back contacts, which maximise the interaction with the light [8]. Progress in optoelectronics is another area where surface plasmon polaritons are playing an increasingly important role [9]. In this issue, researchers at the Institut des Sciences Mole culaire d''Orsay demonstrate that it is possible to excite propagating surface plasmon polaritons with a scanning tunnelling microscope, and detect them [2]. Their work also investigates the nature of the excited plasmons and how the intensities of the propagating surface plasmon polaritons and the localized plasmon emission can be enhanced by factors of 2 and 20 respectively by using a silver tip instead of a tungsten one. Wisdom may be worth more than silver and gold, but a little silver and gold can contribute a lot to unearthing new wisdom at the nanoscale. References [1] Wood R M 1902 Nanotechnology 18 296 [2] Wang T, Boer-Duchemin E, Zhang Y, Comtet G and Dujardin G 2011 Nanotechnology 22 175201 [3] Oates T W H and Mucklich A 2005 Nanotechnology 16 2606 [4] Bosman M, Keast V J, Watanabe M, Maaroof A I and Cortie M B 2007 Nanotechnology 18 165505 [5] Zin M T, Leong K, Wong N-Y, Ma H, Sarikaya M and Jen A K-Y 2009 Nanotechnology 20 015305 [6] Cade N I, Ritman-Meer T, Kwakwa K A and Richards D 2009 Nanotechnology 20 285201 [7] Lukianova-Hleb E Y, Hanna E Y, Hafner J H and Lapotko D O 2010 Nanotechnology 21 085102 [8] Ferry V E, Verschuuren M A, Li H B T, Verhagen E, Walters R J, Schropp R E I, Atwater H A, and Polman A 2010 Optics Express 18 A237-45 [9] Maier S A 2006 IEEE J. Sel. Top. Quantum Electron. 12 1671-7 [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
210. Letters.
- Subjects
- *
LETTERS to the editor , *CURIOSITIES & wonders , *MINERAL collecting , *MINES & mineral resources , *GEMS & precious stones , *CONFERENCES & conventions - Abstract
Several letters to the editor are presented in response to articles including "Mineral Oddities" by Robert Cook in the January/February 2009 issue and "Spessartine from Navegadora Mine, Minas Gerais, Brazil" by John White in the January/February 2009 issue, and one which calls for papers for the Gem and Mineral Show on February 13, 2010.
- Published
- 2009
- Full Text
- View/download PDF
211. Exchange interaction and conductivity in ferroelectric hexaferrite
- Author
-
Novák, Pavel and Knížek, Karel
- Subjects
- *
COLD (Temperature) , *ZINC , *GEMS & precious stones , *MINERALS , *FORTUNE-telling by precious stones - Abstract
Abstract: Ba0.5Sr1.5Zn2Fe12O22 is a new promising multiferroic compound in which the existence of electric polarization is conditioned by the noncollinear arrangement of the iron spins. In principle, ferroelectricity might be present above the room temperature, but electrical conductivity prevents its observation at temperatures higher than ≈130K. Our recent calculations showed that the electronic structure and in particular the conductivity is strongly influenced by relative fractions of iron and zinc in the tetrahedral sublattice of the spinel block in corresponding Y hexaferrite structure. In this paper, we show that the same holds for the exchange interactions. Dependence of the exchange integrals on the distribution of iron and zinc in the tetrahedral sublattice of the spinel block and on the content of Sr in Ba2− x Sr x Zn2Fe12O22 system is calculated using the ab initio approach with an improved treatment of strongly correlated 3d electrons of iron ions. The interaction between the two magnetic blocks that is decisive for the phase diagram is analysed in details. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
212. Site preference and local geometry of Sc in garnets: Part II. The crystal-chemistry of octahedral Sc in the andradite-Ca3Sc2Si3 O12 join.
- Author
-
Quartieri, Simona, Oberti, Roberta, Boiocchi, Massimo, Dalconi, Maria Chiara, Boscherini, Federico, Safonova, Olga, and Woodland, Alan B.
- Subjects
- *
SCANDIUM , *GARNET , *GEMS & precious stones , *POLYHEDRA , *CALCIUM silicates - Abstract
Investigation of scandium incorporation in garnets along the synthetic Ca3Fe23+Si3O12-Ca3Sc2Si3O12 (adr--CaSc) join, based on the same multi-technique approach used in the companion paper (Oberti et al. 2006a), shows that (1) Sc is incorporated exclusively at the Y octahedron; (2) the local coordination of Sc is slightly different in Sc-poor than in Sc-rich compositions (Sc-O = 2.06 Å in CaSc10 vs. 2.10 Å in CaSc30-90); (3) the local coordination of Ca is also slightly different in Sc-poor than in Sc-rich compositions [Ca1,2-O are 2.34(2) and 2.48(2) Å in CaSc10 and 2.36(2) and 2.50(2) Å in CaSc90, with Δ fixed at 0.14 Å in all the samples]; (4) the linear increase of the unit-cell edge along the join derives from multiple changes in the geometry of the different polyhedra and from the rotation of the tetrahedron around the 4̅ axis (α rotation), and cannot be modeled from extrapolation of the behavior observed along the Ca3Al2Si3O12-Ca3Fe23+Si3O12 (grs--adr) join. CaSc-rich garnets, where a large X dodecahedron coexists with a large Y octahedron and a Z tetrahedron occupied by Si, similar to pyrope-grossular garnets, have the highest a values observed to date in calcium silicate garnets. Slightly lower α values are observed in pyrope and almandine, but correspond to a different structural arrangement, where a small X dodecahedron coexists with a small Y octahedron. These results further confirm the efficiency of a combined short- and long-range approach for understanding the properties of garnet solid solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
213. Mn-tourmaline crystals from island of Elba (Italy): Growth history and growth marks.
- Author
-
Agrosì, Giovanna, Bosi, Ferdinando, Lucchesi, Sergio, Melchiorre, Giovanni, and Scandale, Eugenio
- Subjects
- *
TOURMALINE , *GEMS & precious stones , *METHACRYLONITRILE , *DISLOCATIONS in crystals , *POWDERS , *CRYSTALLIZATION , *CRYSTAL growth - Abstract
The growth history reconstruction of tourmaline macro-crystals from pegmatite pockets in the aplite veins of Grotta d.Oggi (island of Elba, Italy) was carried out using a multi-disciplinary and multi-analytical approach [X-ray diffraction topography (XRDT) and electron microprobe analysis (EMPA)]. The work covered in this paper is closely related to the previous crystal-chemical characterization of the same macro-crystals (Bosi et al. 2005). The tourmalines examined here are bi-colored crystals exhibiting greenish-yellow to colorless zoning perpendicular to and parallel to the c axis: the transition from the inner yellow regions to the colorless ones occurs suddenly. XRDT and EMPA studies show relationships between color and chemical zoning and crystal growth evolution, thus identifying two main growth stages, which developed under different conditions. The first stage corresponds to greenish-yellow Mn-tourmaline grown as a result of a 2D-growth mechanism in a F-rich pegmatitic environment; the second one corresponds to colorless elbaitic tourmaline, which developed chiefly by a spiral growth mechanism in an OH-rich hydrothermal environment. The structural defects found in greenish-yellow Mn-tourmaline (growth bands, absence of dislocations, near-uniform chemical element concentrations) are the same as those observed in beryl crystals from pegmatite pockets of the island of Elba. Therefore these features are growth marks that characterize the pegmatitic crystallization stage and differentiate it from the hydrothermal stage, in which the dislocations normal to the growing faces occurred. Hence, the role of tourmaline as a petrogenetic indicator can be extended from chemical composition to crystal growth, reflecting both chemical environment and growth mechanism, and contributing to a better understanding of mineral genesis in pegmatitic crystallization. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
214. Optical and electronic properties of heavily boron-doped homo-epitaxial diamond.
- Author
-
E. Bustarret, E. Gheeraert, and K. Watanabe
- Subjects
DIAMONDS ,GEMS & precious stones ,PHONONS ,RAMAN spectroscopy ,SEMICONDUCTORS - Abstract
The electronic properties of heavily doped (10
20 1021 [B]/cm3 ) p+ diamond epilayers have been investigated in the article [1] featured as Editor's choice of the present issue. Free holes affect strongly the room-temperature optical response of such monocrystalline films in the range of phonon energies. This is illustrated by the IR reflectance and edge-view micro-Raman polarized scattering spectra shown in the cover figure. The corresponding author, Etienne Bustarret, heads the Semiconductors Group of the Laboratoire d'Etudes des Propriétés Electroniques des Solides of CNRS in Grenoble, focusing on the growth of diamond and on the structural and optical properties of epitaxially grown layers and devices based on silicon carbide, diamond or nitrides. The paper was presented as an invited lecture at the 8th International Workshop on Surface and Bulk Defects in CVD Diamond Films (SBDD VIII), held in Diepenbeek-Hasselt, Belgium, 2628 February 2003. [ABSTRACT FROM AUTHOR]- Published
- 2003
- Full Text
- View/download PDF
215. THIS MONTH IN ODYSSEY.
- Subjects
GEMS & precious stones ,KRATERS - Abstract
The article discusses various papers published within the issue, including one on images of precious gemstones, and another on unusual "shocked" rocks found at the site of crater impacts.
- Published
- 2010
216. Robots with a keen eye for shape and colour.
- Author
-
Macklem, Katherine
- Subjects
- *
ROBOTS , *DIAMONDS , *GEMS & precious stones , *MINES & mineral resources ,DEVELOPING countries - Abstract
Machines programmed to cut and polish diamonds. Uri Ariel places on the table a tidy package made of waxy-white paper folded into a rectangle the size of a small envelope. He gingerly opens it to reveal dozens of shiny rough diamonds. Worth $137,000, they range in size from one to 2.5 carats. "Pick one," he says. Ariel, president and CEO of HRA Investments Ltd., operates the first diamond cutting and polishing operation of its kind in North America. Almost the entire global supply of diamonds is cut and polished by people hunched over thick magnifying glasses, many located in Third World countries. But here, in a 10- by 12-foot room on the 21st floor of a downtown Vancouver office tower, are more than two dozen appliances, each smaller than a home sewing machine. They are robots, programmed to cut and polish diamonds. "This," says Ariel, "is the future.".
- Published
- 2003
217. A crook's best friend.
- Subjects
- *
DIAMOND sales & prices , *TERRORISTS , *WHITE collar crimes , *INTERNATIONAL trade , *GEMS & precious stones - Abstract
European intelligence agencies said that al-Qaeda terrorists had used diamonds to move financial resources secretly around the world. Rebels in African countries such as Sierra Leone, Liberia, Angola and the Democratic Republic of Congo have long traded diamonds, timber and other minerals to pay for their weaponry. In the late 1990s United Nations sanctions on doing business with African rebel armies such as UNITA did stop De Beers buying, but other traders filled the gap. South Africa's government, the World Diamond Council and other interested groups have created a system of certificates, known as the Kimberley process, that is supposed to create a paper-trail from mine to store.
- Published
- 2003
218. Untitled.
- Subjects
- *
GOVERNMENT policy , *GOVERNMENT publications , *GEMS & precious stones - Abstract
Presents information on two issues on government regulations in 1941. Information on the America Must Choose white paper of U.S. Vice President Henry A. Wallace regarding the people in the U.S.; Explanation behind the freedom of Japanese stones to complain.
- Published
- 1941
219. The Tariff-Makers.
- Subjects
TARIFF laws ,GEMS & precious stones ,HANDKERCHIEFS - Published
- 1929
220. Diamonds on Ice.
- Author
-
Kramer, Andrew E.
- Subjects
- *
RECESSIONS , *STEEL , *DIAMONDS , *GEMS & precious stones , *BAGS - Abstract
The global recession sapped demand for all kinds of commodities -- like steel and grain -- yet small burlap bags are still arriving by the planeload at Russia's state-owned diamond company. Each day, the contents of the bags spill into the stainless steel hoppers of the receiving room. The diamonds are washed and sorted by size, clarity, shape and quality; then, rather than being sent to be sold around the world, they are wrapped in paper and whisked away to a vault -- about three million carats worth of gems every month. [ABSTRACT FROM PUBLISHER]
- Published
- 2009
221. Diary Offers More On Tanzanite, Al Qaeda Link.
- Author
-
Simpson, Glenn R. and Block, Robert
- Subjects
- *
TANZANITE , *GEMS & precious stones , *TERRORISM financing , *INTERNATIONAL trade - Abstract
Reports on a link between the al Qaeda terrorist network and tanzanite trade. How investigators discovered the link upon examination of papers of Wadih el Hage, a former personal secretary to Osama bin Laden; Move by jewelery retailers Zale Corp., QVC Inc., and Tiffany & Co. to suspend sales of the pale blue gemstone; Investigations by the United States National Security Council, Central Intelligence Agency (CIA) and Customs Service.
- Published
- 2002
222. COSENTINO GROUP BRINGS TOGETHER TOP NORTH AMERICAN CUSTOMERS...
- Subjects
QUARTZ ,GEMS & precious stones - Abstract
Information about several papers discussed at the annual Cosentino 100 conference held in Puerto Vallarta, Mexico from January 19-22, 2014 to discuss about the production and distribution of natural stone, quartz, recycled and architectural surfaces is presented.
- Published
- 2014
223. Cecula's Splendour.
- Author
-
Beare, Stephanie K.
- Subjects
- *
ARTISTS , *CORUNDUM , *GEMS & precious stones , *CERAMIC materials , *ART materials , *OPTICAL properties , *ART objects , *ART & science - Abstract
The article focuses on the investigation of artist Marek Cecula on the transformational essence of corundum as an advanced ceramic material. According to the author, Cecula's curiosity about the relationship between science and art led him to visit various places including Israel, New York City and Brazil. She denotes that Cecula's "Corundum Collection" of art works, particularly vessels, are embedded by the optical properties of the corundum. She states that the transformational aspect of Cecula's art works relative to the use of corundum is linked to the scientific laws of matter.
- Published
- 2003
224. Easy Diamond Trading Set to Be Available for First Time.
- Author
-
Ramkumar, Amrith
- Subjects
- *
DIAMONDS , *ARTIFICIAL diamonds , *GEMS & precious stones , *COVID-19 pandemic , *PAPER money - Published
- 2020
225. Byeoru (Ink Stone).
- Subjects
INK-stones ,GEMS & precious stones ,STONE implements ,ART materials ,ARTISTS' tools - Abstract
The article provides information about byeoru, considered as one of the precious stones mentioned in munbang sau. Byeoru is a stationery implement that is used for making ink which is needed in the creation of siseohwa or works of poetry, painting and calligraphy. It notes that you can create liquid ink by rubbing an ink stick in water on the surface of byeoru known as yeondang. It cites that byeoru has a variety of shapes, forms, and often have various designs such as dragon and cane.
- Published
- 2008
226. Unstrung History.
- Author
-
Lange, Karen E.
- Subjects
- *
GEMS & precious stones , *PRECIOUS metals , *BEADS , *ART materials , *SHELL beads , *JEWELRY , *HISTORY - Abstract
This article describes how ornamental beads can be valuable historical and archeological artifacts. Some date as far back as 100,000 years ago, and every civilization since has used them since. They have been fashioned out of shells, glass, stone, and gems. There were also a valuable trading commodity.
- Published
- 2007
227. NEBULAR ALTERATION AND GEMS.
- Author
-
Gainsforth, Z., Butterworth, A. L., and Westphal, A. J.
- Subjects
NEBULAE ,GEMS & precious stones - Published
- 2017
228. SILICON XANES ASSESSMENT OF THE SILICONE OIL CONTENT OF GEMS IN IDPS.
- Author
-
Flynn, G. J., Wirick, S., Butterworth, A. L., Gainsforth, Z., Westphal, A. J., Kaulich, B., Araki, T., Abyaneh, M., and Tyliszczak, T.
- Subjects
SILICON ,GEMS & precious stones ,INTERPLANETARY dust - Published
- 2017
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.